Exhibit 4.7


 


EXHIBIT C


 


NEITHER THIS SECURITY NOR THE SECURITIES
FOR WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF
ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”),
AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT
TO AN AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE
WITH APPLICABLE STATE SECURITIES LAWS. THIS SECURITY AND THE SECURITIES ISSUABLE UPON EXERCISE OF THIS SECURITY MAY BE PLEDGED IN CONNECTION
WITH A BONA FIDE MARGIN ACCOUNT OR OTHER LOAN SECURED BY SUCH SECURITIES.


 


COMMON STOCK PURCHASE WARRANT


 


CLEANTECH ACQUISITION CORP.


 


	Warrant Shares: _____	Initial Exercise Date: ____ , 2022



 


THIS COMMON STOCK
PURCHASE WARRANT (the “Warrant”) certifies that, for value received, ____________ or its assigns (the
“Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter
set forth, at any time on or after the date hereof (the “Initial Exercise Date”) and on or prior to 5:00 p.m.
(New York City time) on _________20321 (the “Termination Date”) but not thereafter, to subscribe for
and purchase from Cleantech Acquisition Corp., a Delaware corporation (the “Company”), up to shares (as subject
to adjustment hereunder, the “Warrant Shares”) of Common Stock. The purchase price of one share of Common Stock
under this Warrant shall be equal to the Exercise Price, as defined in Section 2(b).


 


Section 1.
Definitions. Capitalized terms used and not otherwise defined herein shall have the meanings set forth in that certain Securities
Purchase Agreement (the “Purchase Agreement”), dated December 16, 2021, among the Company and the purchasers signatory
thereto.


 


Section 2. Exercise.


 


a) Exercise
of Warrant. Exercise of the purchase rights represented by this Warrant may be made, in whole or in part, at any time or times
on or after the Initial Exercise Date and on or before the Termination Date by delivery to the Company of a duly executed facsimile
copy or PDF copy submitted by e-mail (or e-mail attachment) of the Notice of Exercise in the form annexed hereto (the
“Notice of Exercise”). Within the earlier of (i) two (2) Trading Days and (ii) the number of Trading Days
comprising the Standard Settlement Period (as defined in Section 2(d)(i) herein) following the date of exercise as aforesaid, the
Holder shall deliver the aggregate Exercise Price for the shares specified in the applicable Notice of Exercise by wire transfer or
cashier’s check drawn on a United States bank unless the cashless exercise procedure specified in Section 2(c) below is
specified in the applicable Notice of Exercise. No ink-original Notice of Exercise shall be required, nor shall any medallion
guarantee (or other type of guarantee or notarization) of any Notice of Exercise be required. Notwithstanding anything herein to the
contrary, the Holder shall not be required to physically surrender this Warrant to the Company until the Holder has purchased all of
the Warrant Shares available hereunder and the Warrant has been exercised in full, in which case, the Holder shall surrender this
Warrant to the Company for cancellation within three (3) Trading Days of the date on which the final Notice of Exercise is delivered
to the Company. Partial exercises of this Warrant resulting in purchases of a portion of the total number of Warrant Shares
available hereunder shall have the effect of lowering the outstanding number of Warrant Shares purchasable hereunder in an amount
equal to the applicable number of Warrant Shares purchased. The Holder and the Company shall maintain records showing the number of
Warrant Shares purchased and the date of such purchases. The Company shall deliver any objection to any Notice of Exercise within
one (1) Business Day of receipt of such notice. The Holder and any assignee, by acceptance of this Warrant, acknowledge and agree
that, by reason of the provisions of this paragraph, following the purchase of a portion of the Warrant Shares hereunder, the number
of Warrant Shares available for purchase hereunder at any given time may be less than the amount stated on the face hereof.


 





 






	1	10 years.



 



     



     


    

 





b) Exercise
Price. The exercise price per share of Common Stock under this Warrant shall be $20.00, subject to adjustment hereunder (the
“Exercise Price”).


 


c) Cashless
Exercise. If at the time of exercise hereof there is no effective registration statement registering, or the prospectus contained
therein is not available for the resale of the Warrant Shares by the Holder, then this Warrant may also be exercised, in whole or in part,
at such time by means of a “cashless exercise” in which the Holder shall be entitled to receive a number of Warrant Shares
equal to the quotient obtained by dividing [(A-B) (X)] by (A), where:


 


(A) = as
applicable: (i) the VWAP on the Trading Day immediately preceding the date of the applicable Notice of Exercise if such Notice of
Exercise is (1) both executed and delivered pursuant to Section 2(a) hereof on a day that is not a Trading Day or (2) both executed
and delivered pursuant to Section 2(a) hereof on a Trading Day prior to the opening of “regular trading hours” (as
defined in Rule 600(b) of Regulation NMS promulgated under the federal securities laws) on such Trading Day, (ii) at the option of
the Holder, either (y) the VWAP on the Trading Day immediately preceding the date of the applicable Notice of Exercise or (z) the
Bid Price of the Common Stock on the principal Trading Market as reported by Bloomberg L.P. (“Bloomberg”) as of
the time of the Holder’s execution of the applicable Notice of Exercise if such Notice of Exercise is executed during
“regular trading hours” on a Trading Day and is delivered within two (2) hours thereafter (including until two (2) hours
after the close of “regular trading hours” on a Trading Day) pursuant to Section 2(a) hereof or (iii) the VWAP on the
date of the applicable Notice of Exercise if the date of such Notice of Exercise is a Trading Day and such Notice of Exercise is
both executed and delivered pursuant to Section 2(a) hereof after the close of “regular trading hours” on such Trading
Day;


 


(B) = the Exercise Price of this Warrant, as adjusted hereunder;
and


 


(X) = the number
of Warrant Shares that would be issuable upon exercise of this Warrant in accordance with the terms of this Warrant if such exercise were
by means of a cash exercise rather than a cashless exercise.


 






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If Warrant Shares
are issued in such a cashless exercise, the parties acknowledge and agree that in accordance with Section 3(a)(9) of the Securities Act,
the Warrant Shares shall take on the characteristics of the Warrants being exercised, and the holding period of the Warrant Shares being
issued may be tacked on to the holding period of this Warrant. The Company agrees not to take any position contrary to this Section 2(c).


 


“Bid
Price” means, for any date, the price determined by the first of the following clauses that applies: (a) if the Common Stock
is then listed or quoted on a Trading Market, the bid price of the Common Stock for the time in question (or the nearest preceding date)
on the Trading Market on which the Common Stock is then listed or quoted as reported by Bloomberg (based on a Trading Day from 9:30 a.m.
(New York City time) to 4:02 p.m. (New York City time)), (b) if OTCQB or OTCQX is not a Trading Market, the volume weighted average price
of the Common Stock for such date (or the nearest preceding date) on OTCQB or OTCQX as applicable, (c) if the Common Stock is not then
listed or quoted for trading on OTCQB or OTCQX and if prices for the Common Stock are then reported on The Pink Open Market (or a similar
organization or agency succeeding to its functions of reporting prices), the most recent bid price per share of the Common Stock so reported,
or (d) in all other cases, the fair market value of a share of Common Stock as determined by an independent appraiser selected in good
faith by the Purchasers of a majority in interest of the Securities then outstanding and reasonably acceptable to the Company, the fees
and expenses of which shall be paid by the Company.


 


“VWAP”
means, for any date, the price determined by the first of the following clauses that applies: (a) if the Common Stock is then listed
or quoted on a Trading Market, the daily volume weighted average price of the Common Stock for such date (or the nearest preceding
date) on the Trading Market on which the Common Stock is then listed or quoted as reported by Bloomberg (based on a Trading Day from
9:30 a.m. (New York City time) to 4:02 p.m. (New York City time)), (b) if OTCQB or OTCQX is not a Trading Market, the volume
weighted average price of the Common Stock for such date (or the nearest preceding date) on OTCQB or OTCQX as applicable, (c) if the
Common Stock is not then listed or quoted for trading on OTCQB or OTCQX and if prices for the Common Stock are then reported in The
Pink Open Market (or a similar organization or agency succeeding to its functions of reporting prices), the most recent bid price
per share of the Common Stock so reported, or (d) in all other cases, the fair market value of a share of Common Stock as determined
by an independent appraiser selected in good faith by the Purchasers of a majority in interest of the Securities then outstanding
and reasonably acceptable to the Company, the fees and expenses of which shall be paid by the Company.


 


Notwithstanding anything
herein to the contrary, on the Termination Date, this Warrant shall be automatically exercised via cashless exercise pursuant to this
Section 2(c).


 






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 d) Mechanics of Exercise.




 


i. Delivery
of Warrant Shares Upon Exercise. The Company shall cause the Warrant Shares purchased hereunder to be transmitted by the
Transfer Agent to the Holder by crediting the account of the Holder’s or its designee’s balance account with The
Depository Trust Company through its Deposit or Withdrawal at Custodian system (“DWAC”) if the Company is then a
participant in such system and either (A) there is an effective registration statement permitting the issuance of the Warrant Shares
to or resale of the Warrant Shares by the Holder or (B) the Warrant Shares are eligible for resale by the Holder without volume or
manner-of-sale limitations pursuant to Rule 144 (assuming cashless exercise of the Warrants), and otherwise by physical delivery of
a certificate, registered in the Company’s share register in the name of the Holder or its designee, for the number of Warrant
Shares to which the Holder is entitled pursuant to such exercise to the address specified by the Holder in the Notice of Exercise by
the date that is the earliest of (i) two (2) Trading Days after the delivery to the Company of the Notice of Exercise, (ii) one (1)
Trading Day after delivery of the aggregate Exercise Price to the Company and (iii) the number of Trading Days comprising the
Standard Settlement Period after the delivery to the Company of the Notice of Exercise (such date, the “Warrant Share
Delivery Date”). Upon delivery of the Notice of Exercise, the Holder shall be deemed for all corporate purposes to have
become the holder of record of the Warrant Shares with respect to which this Warrant has been exercised, irrespective of the date of
delivery of the Warrant Shares, provided that payment of the aggregate Exercise Price (other than in the case of a cashless
exercise) is received within the earlier of (i) two (2) Trading Days and (ii) the number of Trading Days comprising the Standard
Settlement Period following delivery of the Notice of Exercise. If the Company fails for any reason to deliver to the Holder the
Warrant Shares subject to a Notice of Exercise by the Warrant Share Delivery Date, the Company shall pay to the Holder, in cash, as
liquidated damages and not as a penalty, for each $1,000 of Warrant Shares subject to such exercise (based on the VWAP of the Common
Stock on the date of the applicable Notice of Exercise), $10 per Trading Day (increasing to $20 per Trading Day on the third Trading
Day after the Warrant Share Delivery Date) for each Trading Day after such Warrant Share Delivery Date until such Warrant Shares are
delivered or Holder rescinds such exercise. The Company agrees to maintain a transfer agent that is a participant in the FAST
program so long as this Warrant remains outstanding and exercisable. As used herein, “Standard Settlement Period”
means the standard settlement period, expressed in a number of Trading Days, on the Company’s primary Trading Market with
respect to the Common Stock as in effect on the date of delivery of the Notice of Exercise.


 


ii. Delivery
of New Warrants Upon Exercise. If this Warrant shall have been exercised in part, the Company shall, at the request of a Holder and
upon surrender of this Warrant certificate, at the time of delivery of the Warrant Shares, deliver to the Holder a new Warrant evidencing
the rights of the Holder to purchase the unpurchased Warrant Shares called for by this Warrant, which new Warrant shall in all other respects
be identical with this Warrant.


 






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iii. Rescission
Rights. If the Company fails to cause the Transfer Agent to transmit to the Holder the Warrant Shares pursuant to Section 2(d)(i)
by the Warrant Share Delivery Date, then the Holder will have the right to rescind such exercise.


 


iv. Compensation
for Buy-In on Failure to Timely Deliver Warrant Shares Upon Exercise. In addition to any other rights available to the Holder,
if the Company fails to cause the Transfer Agent to transmit to the Holder the Warrant Shares in accordance with the provisions of
Section 2(d)(i) above pursuant to an exercise on or before the Warrant Share Delivery Date, and if after such date the Holder is
required by its broker to purchase (in an open market transaction or otherwise) or the Holder’s brokerage firm otherwise
purchases, shares of Common Stock to deliver in satisfaction of a sale by the Holder of the Warrant Shares which the Holder
anticipated receiving upon such exercise (a “Buy-In”), then the Company shall (A) pay in cash to the Holder the
amount, if any, by which (x) the Holder’s total purchase price (including brokerage commissions, if any) for the shares of
Common Stock so purchased exceeds (y) the amount obtained by multiplying (1) the number of Warrant Shares that the Company was
required to deliver to the Holder in connection with the exercise at issue times (2) the price at which the sell order giving rise
to such purchase obligation was executed, and (B) at the option of the Holder, either reinstate the portion of the Warrant and
equivalent number of Warrant Shares for which such exercise was not honored (in which case such exercise shall be deemed rescinded)
or deliver to the Holder the number of shares of Common Stock that would have been issued had the Company timely complied with its
exercise and delivery obligations hereunder. For example, if the Holder purchases Common Stock having a total purchase price of
$11,000 to cover a Buy-In with respect to an attempted exercise of shares of Common Stock with an aggregate sale price giving rise
to such purchase obligation of $10,000, under clause (A) of the immediately preceding sentence the Company shall be required to pay
the Holder $1,000. The Holder shall provide the Company written notice indicating the amounts payable to the Holder in respect of
the Buy-In and, upon request of the Company, evidence of the amount of such loss. Nothing herein shall limit a Holder’s right
to pursue any other remedies available to it hereunder, at law or in equity including, without limitation, a decree of specific
performance and/or injunctive relief with respect to the Company’s failure to timely deliver shares of Common Stock upon
exercise of the Warrant as required pursuant to the terms hereof.


 


v. No
Fractional Shares or Scrip. No fractional shares or scrip representing fractional shares shall be issued upon the exercise of this
Warrant. As to any fraction of a share which the Holder would otherwise be entitled to purchase upon such exercise, the Company shall,
at its election, either pay a cash adjustment in respect of such final fraction in an amount equal to such fraction multiplied by the
Exercise Price or round up to the next whole share.


 


vi. Charges,
Taxes and Expenses. Issuance of Warrant Shares shall be made without charge to the Holder for any issue or transfer tax or other incidental
expense in respect of the issuance of such Warrant Shares, all of which taxes and expenses shall be paid by the Company, and such Warrant
Shares shall be issued in the name of the Holder or in such name or names as may be directed by the Holder; provided, however,
that, in the event that Warrant Shares are to be issued in a name other than the name of the Holder, this Warrant when surrendered for
exercise shall be accompanied by the Assignment Form attached hereto duly executed by the Holder and the Company may require, as a condition
thereto, the payment of a sum sufficient to reimburse it for any transfer tax incidental thereto. The Company shall pay all Transfer Agent
fees required for same-day processing of any Notice of Exercise and all fees to the Depository Trust Company (or another established clearing
corporation performing similar functions) required for same-day electronic delivery of the Warrant Shares.


 






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vii. Closing
of Books. The Company will not close its stockholder books or records in any manner which prevents the timely exercise of this Warrant,
pursuant to the terms hereof.


 


e) Holder’s
Exercise Limitations. The Company shall not effect any exercise of this Warrant, and a Holder shall not have the right to exercise
any portion of this Warrant, pursuant to Section 2 or otherwise, to the extent that after giving effect to such issuance after exercise
as set forth on the applicable Notice of Exercise, the Holder (together with the Holder’s Affiliates, and any other Persons acting
as a group together with the Holder or any of the Holder’s Affiliates (such Persons, “Attribution Parties”)),
would beneficially own in excess of the Beneficial Ownership Limitation (as defined below). For purposes of the foregoing sentence, the
number of shares of Common Stock beneficially owned by the Holder and its Affiliates and Attribution Parties shall include the number
of shares of Common Stock issuable upon exercise of this Warrant with respect to which such determination is being made, but shall exclude
the number of shares of Common Stock which would be issuable upon (i) exercise of the remaining, nonexercised portion of this Warrant
beneficially owned by the Holder or any of its Affiliates or Attribution Parties and (ii) exercise or conversion of the unexercised or
nonconverted portion of any other securities of the Company (including, without limitation, any other Common Stock Equivalents) subject
to a limitation on conversion or exercise analogous to the limitation contained herein beneficially owned by the Holder or any of its
Affiliates or Attribution Parties. Except as set forth in the preceding sentence, for purposes of this Section 2(e), beneficial ownership
shall be calculated in accordance with Section 13(d) of the Exchange Act and the rules and regulations promulgated thereunder, it being
acknowledged by the Holder that the Company is not representing to the Holder that such calculation is in compliance with Section 13(d)
of the Exchange Act and the Holder is solely responsible for any schedules required to be filed in accordance therewith. To the extent
that the limitation contained in this Section 2(e) applies, the determination of whether this Warrant is exercisable (in relation to
other securities owned by the Holder together with any Affiliates and Attribution Parties) and of which portion of this Warrant is exercisable
shall be in the sole discretion of the Holder, and the submission of a Notice of Exercise shall be deemed to be the Holder’s determination
of whether this Warrant is exercisable (in relation to other securities owned by the Holder together with any Affiliates and Attribution
Parties) and of which portion of this Warrant is exercisable, in each case subject to the Beneficial Ownership Limitation, and the Company
shall have no obligation to verify or confirm the accuracy of such determination. In addition, a determination as to any group status
as contemplated above shall be determined in accordance with Section 13(d) of the Exchange Act and the rules and regulations promulgated
thereunder. For purposes of this Section 2(e), in determining the number of outstanding shares of Common Stock, a Holder may rely on
the number of outstanding shares of Common Stock as reflected in (A) the Company’s most recent periodic or annual report filed
with the Commission, as the case may be, (B) a more recent public announcement by the Company or (C) a more recent written notice by
the Company or the Transfer Agent setting forth the number of shares of Common Stock outstanding. Upon the written or oral request of
a Holder, the Company shall within one Trading Day confirm orally and in writing to the Holder the number of shares of Common Stock then
outstanding. In any case, the number of outstanding shares of Common Stock shall be determined after giving effect to the conversion
or exercise of securities of the Company, including this Warrant, by the Holder or its Affiliates or Attribution Parties since the date
as of which such number of outstanding shares of Common Stock was reported. The “Beneficial Ownership Limitation”
shall be [9.99/4.99%] of the number of shares of the Common Stock outstanding immediately after giving effect to the issuance of shares
of Common Stock issuable upon exercise of this Warrant. The Holder, upon notice to the Company, may increase or decrease the Beneficial
Ownership Limitation provisions of this Section 2(e), provided that the Beneficial Ownership Limitation in no event exceeds 9.99% of
the number of shares of the Common Stock outstanding immediately after giving effect to the issuance of shares of Common Stock upon exercise
of this Warrant held by the Holder and the provisions of this Section 2(e) shall continue to apply. Any increase in the Beneficial Ownership
Limitation will not be effective until the 61st day after such notice is delivered to the Company. The provisions of this
paragraph shall be construed and implemented in a manner otherwise than in strict conformity with the terms of this Section 2(e) to correct
this paragraph (or any portion hereof) which may be defective or inconsistent with the intended Beneficial Ownership Limitation herein
contained or to make changes or supplements necessary or desirable to properly give effect to such limitation. The limitations contained
in this paragraph shall apply to a successor holder of this Warrant.


 






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Section 3. Certain Adjustments.


 


a) Stock
Dividends and Splits. If the Company, at any time while this Warrant is outstanding: (i) pays a stock dividend or otherwise makes
a distribution or distributions on shares of its Common Stock or any other equity or equity equivalent securities payable in shares of
Common Stock (which, for avoidance of doubt, shall not include any shares of Common Stock issued by the Company upon exercise of this
Warrant), (ii) subdivides outstanding shares of Common Stock into a larger number of shares, (iii) combines (including by way of reverse
stock split) outstanding shares of Common Stock into a smaller number of shares, or (iv) issues by reclassification of shares of the Common
Stock any shares of capital stock of the Company, then in each case the Exercise Price shall be multiplied by a fraction of which the
numerator shall be the number of shares of Common Stock (excluding treasury shares, if any) outstanding immediately before such event
and of which the denominator shall be the number of shares of Common Stock outstanding immediately after such event, and the number of
shares issuable upon exercise of this Warrant shall be proportionately adjusted such that the aggregate Exercise Price of this Warrant
shall remain unchanged. Any adjustment made pursuant to this Section 3(a) shall become effective immediately after the record date for
the determination of stockholders entitled to receive such dividend or distribution and shall become effective immediately after the effective
date in the case of a subdivision, combination or re-classification.


 


b) Subsequent
Equity Sales. If the Company or any Subsidiary thereof, as applicable, at any time while this Warrant is outstanding, shall
sell, enter into an agreement to sell, or grant any option to purchase, or sell or grant any right to reprice, or otherwise dispose
of or issue (or announce any offer, sale, grant or any option to purchase or other disposition) any Common Stock or Common Stock
Equivalents, at an effective price per share less than the Exercise Price then in effect (such lower price, the “Base Share
Price” and such issuances collectively, a “Dilutive Issuance”) (it being understood and agreed that if
the holder of the Common Stock or Common Stock Equivalents so issued shall at any time, whether by operation of purchase price
adjustments, reset provisions, floating conversion, exercise or exchange prices or otherwise, or due to warrants, options or rights
per share which are issued in connection with such issuance, be entitled to receive shares of Common Stock at an effective price per
share that is less than the Exercise Price, such issuance shall be deemed to have occurred for less than the Exercise Price on such
date of the Dilutive Issuance at such effective price), then simultaneously with the consummation (or, if earlier, the announcement)
of each Dilutive Issuance the Exercise Price shall be reduced and only reduced to equal the Base Share Price and the number of
Warrant Shares issuable hereunder shall be increased such that the aggregate Exercise Price payable hereunder, after taking into
account the decrease in the Exercise Price, shall be equal to the aggregate Exercise Price prior to such adjustment, provided that
the Base Share Price shall not be less than $2.00 (subject to adjustment for reverse and forward stock splits, recapitalizations and
similar transactions following the date of the Purchase Agreement). Notwithstanding the foregoing, no adjustments shall be made,
paid or issued under this Section 3(b) in respect of an Exempt Issuance. The Company shall notify the Holder, in writing, no later
than the Trading Day following the issuance or deemed issuance of any Common Stock or Common Stock Equivalents subject to this
Section 3(b), indicating therein the applicable issuance price, or applicable reset price, exchange price, conversion price and
other pricing terms (such notice, the “Dilutive Issuance Notice”). For purposes of clarification, whether or not
the Company provides a Dilutive Issuance Notice pursuant to this Section 3(b), upon the occurrence of any Dilutive Issuance, the
Holder is entitled to receive a number of Warrant Shares based upon the Base Share Price regardless of whether the Holder accurately
refers to the Base Share Price in the Notice of Exercise. If the Company enters into a Variable Rate Transaction, the Company shall
be deemed to have issued Common Stock or Common Stock Equivalents at the lowest possible price, conversion price or exercise price
at which such securities may be issued, converted or exercised.


 






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c) Subsequent
Rights Offerings. In addition to any adjustments pursuant to Section 3(a) above, if at any time the Company grants, issues or
sells any Common Stock Equivalents or rights to purchase stock, warrants, securities or other property pro rata to the record
holders of any class of shares of Common Stock (the “Purchase Rights”), then the Holder will be entitled to
acquire, upon the terms applicable to such Purchase Rights, the aggregate Purchase Rights which the Holder could have acquired if
the Holder had held the number of shares of Common Stock acquirable upon complete exercise of this Warrant (without regard to any
limitations on exercise hereof, including without limitation, the Beneficial Ownership Limitation) immediately before the date on
which a record is taken for the grant, issuance or sale of such Purchase Rights, or, if no such record is taken, the date as of
which the record holders of shares of Common Stock are to be determined for the grant, issue or sale of such Purchase Rights
(provided, however, that, to the extent that the Holder’s right to participate in any such Purchase Right would
result in the Holder exceeding the Beneficial Ownership Limitation, then the Holder shall not be entitled to participate in such
Purchase Right to such extent (or beneficial ownership of such shares of Common Stock as a result of such Purchase Right to such
extent) and such Purchase Right to such extent shall be held in abeyance for the Holder until such time, if ever, as its right
thereto would not result in the Holder exceeding the Beneficial Ownership Limitation).


 


d) Pro
Rata Distributions. During such time as this Warrant is outstanding, if the Company shall declare or make any dividend or other distribution
of its assets (or rights to acquire its assets) to holders of shares of Common Stock, by way of return of capital or otherwise (including,
without limitation, any distribution of cash, stock or other securities, property or options by way of a dividend, spin off, reclassification,
corporate rearrangement, scheme of arrangement or other similar transaction) (a “Distribution”), at any time after
the issuance of this Warrant, then, in each such case, the Holder shall be entitled to participate in such Distribution to the same extent
that the Holder would have participated therein if the Holder had held the number of shares of Common Stock acquirable upon complete exercise
of this Warrant (without regard to any limitations on exercise hereof, including without limitation, the Beneficial Ownership Limitation)
immediately before the date of which a record is taken for such Distribution, or, if no such record is taken, the date as of which the
record holders of shares of Common Stock are to be determined for the participation in such Distribution (provided, however,
that, to the extent that the Holder's right to participate in any such Distribution would result in the Holder exceeding the Beneficial
Ownership Limitation, then the Holder shall not be entitled to participate in such Distribution to such extent (or in the beneficial ownership
of any shares of Common Stock as a result of such Distribution to such extent) and the portion of such Distribution shall be held in abeyance
for the benefit of the Holder until such time, if ever, as its right thereto would not result in the Holder exceeding the Beneficial Ownership
Limitation). To the extent that this Warrant has not been partially or completely exercised at the time of such Distribution, such portion
of the Distribution shall be held in abeyance for the benefit of the Holder until the Holder has exercised this Warrant.


 






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e) Fundamental
Transaction. If, at any time while this Warrant is outstanding, (i) the Company, directly or indirectly, in one or more related
transactions effects any merger or consolidation of the Company with or into another Person, (ii) the Company (or any Subsidiary),
directly or indirectly, effects any sale, lease, license, assignment, transfer, conveyance or other disposition of all or
substantially all of its assets in one or a series of related transactions, (iii) any, direct or indirect, purchase offer, tender
offer or exchange offer (whether by the Company or another Person) is completed pursuant to which holders of Common Stock are
permitted to sell, tender or exchange their shares for other securities, cash or property and has been accepted by the holders of
50% or more of the outstanding Common Stock, (iv) the Company, directly or indirectly, in one or more related transactions effects
any reclassification, reorganization or recapitalization of the Common Stock or any compulsory share exchange pursuant to which the
Common Stock is effectively converted into or exchanged for other securities, cash or property, or (v) the Company, directly or
indirectly, in one or more related transactions consummates a stock or share purchase agreement or other business combination
(including, without limitation, a reorganization, recapitalization, spin-off, merger or scheme of arrangement) with another Person
or group of Persons whereby such other Person or group acquires more than 50% of the outstanding shares of Common Stock (not
including any shares of Common Stock held by the other Person or other Persons making or party to, or associated or affiliated with
the other Persons making or party to, such stock or share purchase agreement or other business combination) (each a
“Fundamental Transaction”), then, upon any subsequent exercise of this Warrant, the Holder shall have the right
to receive, for each Warrant Share that would have been issuable upon such exercise immediately prior to the occurrence of such
Fundamental Transaction, at the option of the Holder (without regard to any limitation in Section 2(e) on the exercise of this
Warrant), the number of shares of Common Stock of the successor or acquiring corporation or of the Company, if it is the surviving
corporation, and any additional consideration (the “Alternate Consideration”) receivable as a result of such
Fundamental Transaction by a holder of the number of shares of Common Stock for which this Warrant is exercisable immediately prior
to such Fundamental Transaction (without regard to any limitation in Section 2(e) on the exercise of this Warrant). For purposes of
any such exercise, the determination of the Exercise Price shall be appropriately adjusted to apply to such Alternate Consideration
based on the amount of Alternate Consideration issuable in respect of one share of Common Stock in such Fundamental Transaction, and
the Company shall apportion the Exercise Price among the Alternate Consideration in a reasonable manner reflecting the relative
value of any different components of the Alternate Consideration. If holders of Common Stock are given any choice as to the
securities, cash or property to be received in a Fundamental Transaction, then the Holder shall be given the same choice as to the
Alternate Consideration it receives upon any exercise of this Warrant following such Fundamental Transaction. Notwithstanding
anything to the contrary, in the event of a Fundamental Transaction, the Company or any Successor Entity (as defined below) shall,
at the Holder’s option, exercisable at any time concurrently with, or within 30 days after, the consummation of the
Fundamental Transaction (or, if later, the date of the public announcement of the applicable Fundamental Transaction), purchase this
Warrant from the Holder by paying to the Holder an amount of cash equal to the Black Scholes Value (as defined below) of the
remaining unexercised portion of this Warrant on the date of the consummation of such Fundamental Transaction; provided, however,
that, if the Fundamental Transaction is not within the Company's control, including not approved by the Company's Board of
Directors, Holder shall only be entitled to receive from the Company or any Successor Entity the same type or form of consideration
(and in the same proportion), at the Black Scholes Value of the unexercised portion of this Warrant, that is being offered and paid
to the holders of Common Stock of the Company in connection with the Fundamental Transaction, whether that consideration be in the
form of cash, stock or any combination thereof, or whether the holders of Common Stock are given the choice to receive from among
alternative forms of consideration in connection with the Fundamental Transaction; provided, further, that if holders
of Common Stock of the Company are not offered or paid any consideration in such Fundamental Transaction, such holders of Common
Stock will be deemed to have received common stock of the Successor Entity (which Entity may be the Company following such
Fundamental Transaction) in such Fundamental Transaction. “Black Scholes Value” means the value of this Warrant
based on the Black-Scholes Option Pricing Model obtained from the “OV” function on Bloomberg determined as of the day of
consummation of the applicable Fundamental Transaction for pricing purposes and reflecting (A) a risk-free interest rate
corresponding to the U.S. Treasury rate for a period equal to the time between the date of the public announcement of the applicable
Fundamental Transaction and the Termination Date, (B) an expected volatility equal to the greater of 100% and the 100 day volatility
obtained from the HVT function on Bloomberg (determined utilizing a 365 day annualization factor) as of the Trading Day immediately
following the public announcement of the applicable Fundamental Transaction, (C) the underlying price per share used in such
calculation shall be the greater of (i) the sum of the price per share being offered in cash, if any, plus the value of any non-cash
consideration, if any, being offered in such Fundamental Transaction and (ii) the highest VWAP during the period beginning on the
Trading Day immediately preceding the announcement of the applicable Fundamental Transaction (or the consummation of the applicable
Fundamental Transaction, if earlier) and ending on the Trading Day of the Holder’s request pursuant to this Section 3(e) and
(D) a remaining option time equal to the time between the date of the public announcement of the applicable Fundamental Transaction
and the Termination Date and (E) a zero cost of borrow. The payment of the Black Scholes Value will be made by wire transfer of
immediately available funds (or such other consideration) within the later of (i) five Business Days of the Holder’s election
and (ii) the date of consummation of the Fundamental Transaction. The Company shall cause any successor entity in a Fundamental
Transaction in which the Company is not the survivor (the “Successor Entity”) to assume in writing all of the
obligations of the Company under this Warrant and the other Transaction Documents in accordance with the provisions of this Section
3(e) pursuant to written agreements in form and substance reasonably satisfactory to the Holder and approved by the Holder (without
unreasonable delay) prior to such Fundamental Transaction and shall, at the option of the Holder, deliver to the Holder in exchange
for this Warrant a security of the Successor Entity evidenced by a written instrument substantially similar in form and substance to
this Warrant which is exercisable for a corresponding number of shares of capital stock of such Successor Entity (or its parent
entity) equivalent to the shares of Common Stock acquirable and receivable upon exercise of this Warrant (without regard to any
limitations on the exercise of this Warrant) prior to such Fundamental Transaction, and with an exercise price which applies the
exercise price hereunder to such shares of capital stock (but taking into account the relative value of the shares of Common Stock
pursuant to such Fundamental Transaction and the value of such shares of capital stock, such number of shares of capital stock and
such exercise price being for the purpose of protecting the economic value of this Warrant immediately prior to the consummation of
such Fundamental Transaction), and which is reasonably satisfactory in form and substance to the Holder. Upon the occurrence of any
such Fundamental Transaction, the Successor Entity shall succeed to, and be substituted for (so that from and after the date of such
Fundamental Transaction, the provisions of this Warrant and the other Transaction Documents referring to the “Company”
shall refer instead to the Successor Entity), and may exercise every right and power of the Company and shall assume all of the
obligations of the Company under this Warrant and the other Transaction Documents with the same effect as if such Successor Entity
had been named as the Company herein.


 






    9



     


    

 


f)  Calculations.
All calculations under this Section 3 shall be made to the nearest cent or the nearest 1/100th of a share, as the case may be. For
purposes of this Section 3, the number of shares of Common Stock deemed to be issued and outstanding as of a given date shall be the
sum of the number of shares of Common Stock (excluding treasury shares, if any) issued and outstanding.


 


 g) Notice to Holder.




 


i.
Adjustment to Exercise Price. Whenever the Exercise Price is adjusted pursuant to any provision of this Section 3, the Company
shall promptly deliver to the Holder by facsimile or email a notice setting forth the Exercise Price after such adjustment and any resulting
adjustment to the number of Warrant Shares and setting forth a brief statement of the facts requiring such adjustment.


 


ii. Notice
to Allow Exercise by Holder. If (A) the Company shall declare a dividend (or any other distribution in whatever form) on the
Common Stock, (B) the Company shall declare a special nonrecurring cash dividend on or a redemption of the Common Stock, (C) the
Company shall authorize the granting to all holders of the Common Stock rights or warrants to subscribe for or purchase any shares
of capital stock of any class or of any rights, (D) the approval of any stockholders of the Company shall be required in connection
with any reclassification of the Common Stock, any consolidation or merger to which the Company (or any of its Subsidiaries) is a
party, any sale or transfer of all or substantially all of its assets, or any compulsory share exchange whereby the Common Stock is
converted into other securities, cash or property, or (E) the Company shall authorize the voluntary or involuntary dissolution,
liquidation or winding up of the affairs of the Company, then, in each case, the Company shall cause to be delivered by facsimile or
email to the Holder at its last facsimile number or email address as it shall appear upon the Warrant Register of the Company, at
least 20 calendar days prior to the applicable record or effective date hereinafter specified, a notice stating (x) the date on
which a record is to be taken for the purpose of such dividend, distribution, redemption, rights or warrants, or if a record is not
to be taken, the date as of which the holders of the Common Stock of record to be entitled to such dividend, distributions,
redemption, rights or warrants are to be determined or (y) the date on which such reclassification, consolidation, merger, sale,
transfer or share exchange is expected to become effective or close, and the date as of which it is expected that holders of the
Common Stock of record shall be entitled to exchange their shares of the Common Stock for securities, cash or other property
deliverable upon such reclassification, consolidation, merger, sale, transfer or share exchange; provided that the failure to
deliver such notice or any defect therein or in the delivery thereof shall not affect the validity of the corporate action required
to be specified in such notice. To the extent that any notice provided in this Warrant constitutes, or contains, material,
non-public information regarding the Company or any of the Subsidiaries, the Company shall simultaneously file such notice with the
Commission pursuant to a Current Report on Form 8-K. The Holder shall remain entitled to exercise this Warrant during the period
commencing on the date of such notice to the effective date of the event triggering such notice except as may otherwise be expressly
set forth herein.


 






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h)
Voluntary Adjustment By Company. Subject to the rules and regulations of the Trading Market, the Company may at any time
during the term of this Warrant, subject to the prior written consent of the Holder, reduce the then current Exercise Price to any amount
and for any period of time deemed appropriate by the board of directors of the Company.


 


Section 4. Transfer of Warrant.


 


a)
Transferability. Subject to compliance with any applicable securities laws and the conditions set forth in Section 4(d)
hereof and to the provisions of Section 4.1 of the Purchase Agreement, this Warrant and all rights hereunder (including, without limitation,
any registration rights) are transferable, in whole or in part, upon surrender of this Warrant at the principal office of the Company
or its designated agent, together with a written assignment of this Warrant substantially in the form attached hereto duly executed by
the Holder or its agent or attorney and funds sufficient to pay any transfer taxes payable upon the making of such transfer. Upon such
surrender and, if required, such payment, the Company shall execute and deliver a new Warrant or Warrants in the name of the assignee
or assignees, as applicable, and in the denomination or denominations specified in such instrument of assignment, and shall issue to the
assignor a new Warrant evidencing the portion of this Warrant not so assigned, and this Warrant shall promptly be cancelled. Notwithstanding
anything herein to the contrary, the Holder shall not be required to physically surrender this Warrant to the Company unless the Holder
has assigned this Warrant in full, in which case, the Holder shall surrender this Warrant to the Company within three (3) Trading Days
of the date on which the Holder delivers an assignment form to the Company assigning this Warrant in full. The Warrant, if properly assigned
in accordance herewith, may be exercised by a new holder for the purchase of Warrant Shares without having a new Warrant issued.


 


b)
New Warrants. This Warrant may be divided or combined with other Warrants upon presentation hereof at the aforesaid office
of the Company, together with a written notice specifying the names and denominations in which new Warrants are to be issued, signed by
the Holder or its agent or attorney. Subject to compliance with Section 4(a), as to any transfer which may be involved in such division
or combination, the Company shall execute and deliver a new Warrant or Warrants in exchange for the Warrant or Warrants to be divided
or combined in accordance with such notice. All Warrants issued on transfers or exchanges shall be dated the Initial Exercise Date and
shall be identical with this Warrant except as to the number of Warrant Shares issuable pursuant thereto.


 


c) Warrant
Register. The Company shall register this Warrant, upon records to be maintained by the Company for that purpose (the
“Warrant Register”), in the name of the record Holder hereof from time to time. The Company may deem and treat
the registered Holder of this Warrant as the absolute owner hereof for the purpose of any exercise hereof or any distribution to the
Holder, and for all other purposes, absent actual notice to the contrary.


 






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d)
Transfer Restrictions. If, at the time of the surrender of this Warrant in connection with any transfer of this Warrant,
the transfer of this Warrant shall not be either (i) registered pursuant to an effective registration statement under the Securities Act
and under applicable state securities or blue sky laws or (ii) eligible for resale without volume or manner-of-sale restrictions or current
public information requirements pursuant to Rule 144, the Company may require, as a condition of allowing such transfer, that the Holder
or transferee of this Warrant, as the case may be, comply with the provisions of Section 5.7 of the Purchase Agreement.


 


e)
Representation by the Holder. The Holder, by the acceptance hereof, represents and warrants that it is acquiring this Warrant
and, upon any exercise hereof, will acquire the Warrant Shares issuable upon such exercise, for its own account and not with a view to
or for distributing or reselling such Warrant Shares or any part thereof in violation of the Securities Act or any applicable state securities
law, except pursuant to sales registered or exempted under the Securities Act.


 


Section 5. Miscellaneous.


 


a)
No Rights as Stockholder Until Exercise; No Settlement in Cash. This Warrant does not entitle the Holder to any voting rights,
dividends or other rights as a stockholder of the Company prior to the exercise hereof as set forth in Section 2(d)(i), except as expressly
set forth in Section 3. Without limiting any rights of a Holder to receive Warrant Shares on a “cashless exercise” pursuant
to Section 2(c) or to receive cash payments pursuant to Section 2(d)(i) and Section 2(d)(iv) herein, in no event shall the Company be
required to net cash settle an exercise of this Warrant.


 


b)
Loss, Theft, Destruction or Mutilation of Warrant. The Company covenants that upon receipt by the Company of evidence reasonably
satisfactory to it of the loss, theft, destruction or mutilation of this Warrant or any stock certificate relating to the Warrant Shares,
and in case of loss, theft or destruction, of indemnity or security reasonably satisfactory to it (which, in the case of the Warrant,
shall not include the posting of any bond), and upon surrender and cancellation of such Warrant or stock certificate, if mutilated, the
Company will make and deliver a new Warrant or stock certificate of like tenor and dated as of such cancellation, in lieu of such Warrant
or stock certificate.


 


c)
Saturdays, Sundays, Holidays, etc. If the last or appointed day for the taking of any action or the expiration of any right
required or granted herein shall not be a Business Day, then such action may be taken or such right may be exercised on the next succeeding
Business Day.


 






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 d) Authorized Shares.







 


The Company
covenants that, during the period the Warrant is outstanding, it will reserve from its authorized and unissued Common Stock a sufficient
number of shares to provide for the issuance of the Warrant Shares upon the exercise of any purchase rights under this Warrant. The Company
further covenants that its issuance of this Warrant shall constitute full authority to its officers who are charged with the duty of issuing
the necessary Warrant Shares upon the exercise of the purchase rights under this Warrant. The Company will take all such reasonable action
as may be necessary to assure that such Warrant Shares may be issued as provided herein without violation of any applicable law or regulation,
or of any requirements of the Trading Market upon which the Common Stock may be listed. The Company covenants that all Warrant Shares
which may be issued upon the exercise of the purchase rights represented by this Warrant will, upon exercise of the purchase rights represented
by this Warrant and payment for such Warrant Shares in accordance herewith, be duly authorized, validly issued, fully paid and nonassessable
and free from all taxes, liens and charges created by the Company in respect of the issue thereof (other than taxes in respect of any
transfer occurring contemporaneously with such issue).


 


Except
and to the extent as waived or consented to by the Holder, the Company shall not by any action, including, without limitation,
amending its certificate of incorporation or through any reorganization, transfer of assets, consolidation, merger, dissolution,
issue or sale of securities or any other voluntary action, avoid or seek to avoid the observance or performance of any of the terms
of this Warrant, but will at all times in good faith assist in the carrying out of all such terms and in the taking of all such
actions as may be necessary or appropriate to protect the rights of Holder as set forth in this Warrant against impairment. Without
limiting the generality of the foregoing, the Company will (i) not increase the par value of any Warrant Shares above the amount
payable therefor upon such exercise immediately prior to such increase in par value, (ii) take all such action as may be necessary
or appropriate in order that the Company may validly and legally issue fully paid and nonassessable Warrant Shares upon the exercise
of this Warrant and (iii) use commercially reasonable efforts to obtain all such authorizations, exemptions or consents from any
public regulatory body having jurisdiction thereof, as may be, necessary to enable the Company to perform its obligations under this
Warrant.


 


Before taking
any action which would result in an adjustment in the number of Warrant Shares for which this Warrant is exercisable or in the Exercise
Price, the Company shall obtain all such authorizations or exemptions thereof, or consents thereto, as may be necessary from any public
regulatory body or bodies having jurisdiction thereof.


 


e)
Jurisdiction. All questions concerning the construction, validity, enforcement and interpretation of this Warrant shall
be determined in accordance with the provisions of the Purchase Agreement.





 


f)
Restrictions. The Holder acknowledges that the Warrant Shares acquired upon the exercise of this Warrant, if not registered,
and the Holder does not utilize cashless exercise, will have restrictions upon resale imposed by state and federal securities laws.


 






    13



     


    

 


g)
Nonwaiver and Expenses. No course of dealing or any delay or failure to exercise any right hereunder on the part of Holder
shall operate as a waiver of such right or otherwise prejudice the Holder’s rights, powers or remedies. Without limiting any other
provision of this Warrant or the Purchase Agreement, if the Company willfully and knowingly fails to comply with any provision of this
Warrant, which results in any material damages to the Holder, the Company shall pay to the Holder such amounts as shall be sufficient
to cover any costs and expenses including, but not limited to, reasonable attorneys’ fees, including those of appellate proceedings,
incurred by the Holder in collecting any amounts due pursuant hereto or in otherwise enforcing any of its rights, powers or remedies hereunder.


 


h)
Notices. Any notice, request or other document required or permitted to be given or delivered to the Holder by the Company
shall be delivered in accordance with the notice provisions of the Purchase Agreement.


 


i)  Limitation
of Liability. No provision hereof, in the absence of any affirmative action by the Holder to exercise this Warrant to purchase
Warrant Shares, and no enumeration herein of the rights or privileges of the Holder, shall give rise to any liability of the Holder
for the purchase price of any Common Stock or as a stockholder of the Company, whether such liability is asserted by the Company or
by creditors of the Company.


 


j)
Remedies. The Holder, in addition to being entitled to exercise all rights granted by law, including recovery of damages,
will be entitled to specific performance of its rights under this Warrant. The Company agrees that monetary damages would not be adequate
compensation for any loss incurred by reason of a breach by it of the provisions of this Warrant and hereby agrees to waive and not to
assert the defense in any action for specific performance that a remedy at law would be adequate.


 


k)
Successors and Assigns. Subject to applicable securities laws, this Warrant and the rights and obligations evidenced hereby
shall inure to the benefit of and be binding upon the successors and permitted assigns of the Company and the successors and permitted
assigns of Holder. The provisions of this Warrant are intended to be for the benefit of any Holder from time to time of this Warrant and
shall be enforceable by the Holder or holder of Warrant Shares.


 


l)
Amendment. This Warrant may be modified or amended or the provisions hereof waived with the written consent of the Company
and the Holder.


 


m) Severability.
Wherever possible, each provision of this Warrant shall be interpreted in such manner as to be effective and valid under applicable
law, but if any provision of this Warrant shall be prohibited by or invalid under applicable law, such provision shall be
ineffective to the extent of such prohibition or invalidity, without invalidating the remainder of such provisions or the remaining
provisions of this Warrant.


 


n)
Headings. The headings used in this Warrant are for the convenience of reference only and shall not, for any purpose, be
deemed a part of this Warrant.


 


********************


 


(Signature Page Follows)





 






    14



     


    

 


IN WITNESS WHEREOF, the Company has
caused this Warrant to be executed by its officer thereunto duly authorized as of the date first above indicated.


 


	 	CLEANTECH ACQUISITION CORP.
	 	 
	 	By:	 
	 	 	Name:	         
	 	 	Title:	 



 






    15



     


    

 


NOTICE OF EXERCISE


 


TO: CLTH


 


(1)
The undersigned hereby elects to purchase _______________ Warrant Shares of the Company pursuant to the terms of the attached
Warrant (only if exercised in full), and tenders herewith payment of the exercise price in full, together with all applicable
transfer taxes, if any.


 


 (2) Payment shall take the form of (check applicable box):


 


☐ in lawful money
of the United States; or


 




☐
if permitted the cancellation of such number of Warrant Shares as is necessary, in accordance with the formula set forth in
subsection 2(c), to exercise this Warrant with respect to the maximum number of Warrant Shares purchasable pursuant to the cashless
exercise procedure set forth in subsection 2(c).


 


(3)
Please issue said Warrant Shares in the name of the undersigned or in such other name as is specified below:


 


_______________________________


 


The Warrant Shares shall be delivered to the following DWAC
Account Number:


 


_______________________________


 


_______________________________


 


_______________________________


 


 


(4)
Accredited Investor. The undersigned is an “accredited investor” as defined in Regulation D promulgated under
the Securities Act of 1933, as amended.


 


[SIGNATURE OF HOLDER]


 


Name of Investing Entity:    ___________________________________________________________________________


Signature
of Authorized Signatory of Investing Entity: _____________________________________________________


  Name of
Authorized Signatory: _______________________________________________________________________


  Title of
Authorized Signatory: ________________________________________________________________________


  Date: __________________________________________________________________________________________


 






     


     


    

 


EXHIBIT B


 


ASSIGNMENT FORM


 


(To assign the foregoing
Warrant, execute this form and supply required information. Do not use this form to purchase shares.)


 


FOR VALUE RECEIVED, the foregoing Warrant and all rights evidenced thereby are hereby assigned to 


 


	Name:	 
		(Please Print)
	 	 
	Address:	 
		(Please Print)
	 	 
	Phone Number:	 
	 	 
	 Email Address:	 


 


Dated:  __________
____,  _____


 


Holder’s Signature: __________________ 


 


Holder’s Address: __________________