Exhibit
4.3


 


DESCRIPTION
OF REGISTRANT’S SECURITIES


 


The following summary
of the material terms of our securities is not intended to be a complete summary of the rights and preferences of such securities.
We urge you to read our charter and bylaws in their entirety for a complete description of the rights and preferences of our securities,
copies of which have been filed with the SEC. 


 


Authorized and Outstanding Stock


 


Our charter authorizes
the issuance of (a) 501,000,000 shares of capital stock, consisting of (x) 500,000,000 authorized shares of common stock,
including (1) 400,000,000 authorized shares of Class A common stock, (2) 100,000,000 authorized shares of Class B
common stock and (y) 1,000,000 authorized shares of preferred stock, par value $0.0001 per share. As of March 17, 2021, there were
15,149,671 shares of Class A common Stock outstanding; (b) 20,130,741 shares of Class B common stock outstanding;
and (c) no shares of preferred stock outstanding.


 


Common Stock


 


Class A common stock


 


Holders of our Class A
common stock are entitled to one vote for each share held on all matters to be voted on by stockholders. Unless specified in our
charter or our bylaws, or as required by the applicable provisions of the DGCL or applicable stock exchange rules, the affirmative
vote of a majority of our outstanding shares of common stock that are voted is required to approve any such matter voted on by
our stockholders. Our Board is divided into three classes, each of which generally serves for a term of three years with only one
class of directors being elected in each year. There is no cumulative voting with respect to the election of directors, with the
result that the holders of more than 50% of the shares voted in the election of directors can elect all of the directors. Our stockholders
are entitled to receive ratable dividends when, as and if declared by the Board out of funds legally available therefor.


 


Class B common stock


 


The Class B common
stock is a voting, non-economic class of common stock, with a par value of $0.0001 per share. Holders of the Class B
common stock vote together as a single class with holders of our Class A common stock on all matters properly submitted to
a vote of the stockholders. The holders of Class B common stock generally have the right to cause Atlas TC Holdings LLC, a
wholly-owned subsidiary of the Company and a Delaware limited liability company (“Holdings”) to redeem all or a portion
of their common units of Holdings (“Holdings Units”) in exchange for shares of the Class A common stock or, at
Holdings’ option, an equivalent amount of cash. Upon the future exchange of Holdings Units held by any holder of Class B
common stock, a corresponding number of shares of Class B common stock held by such holder of Class B common stock will
be canceled. Our charter provides that Class B common stock is not be entitled to receive dividends, if declared by our Board,
or to receive any portion of any such assets in respect of their shares upon liquidation, dissolution, distribution of assets or
winding up of the post-combination company.


 


Voting Power


 


Except as otherwise
required by law or as otherwise provided in any certificate of designation for any series of preferred stock, the holders of our
common stock will possess all voting power for the election of the Company’s directors and all other matters requiring stockholder
action and will at all times vote together as one class on all matters submitted to a vote of the stockholders of the Company.
Holders of our common stock are entitled to one vote per share on matters to be voted on by stockholders.


 


Dividends


 


Holders of Class A
common stock will be entitled to receive such dividends and other distributions, if any, as may be declared from time to time by
our Board in our discretion out of funds legally available therefor and shall share equally on a per share basis in such dividends
and distributions. Holders of Class B common stock are not entitled to share in any such dividends or other distributions.


 






     


     


    

 


Liquidation, Dissolution and Winding-Up


 


In the event of the
voluntary or involuntary liquidation, dissolution, distribution of assets or winding up of the Company, the holders of Class A
common stock will be entitled to receive an equal amount per share of all of the Company’s assets of whatever kind available
for distribution to stockholders, after the rights of the holders of the preferred stock have been satisfied and after payment
or provision for payment of the debts and other liabilities of the Company. Holders of Class B common stock are not entitled
to receive any portion of any such assets in respect of their shares of Class B common stock.


 


Preemptive or Other Rights


 


The Company’s
stockholders have no preemptive or other subscription rights and there are no sinking fund or redemption provisions applicable
to the common stock.


 


Election of Directors


 


The Board is classified
into three classes, designated as Class I, Class II and Class III. Messrs. Ferraioli and Boyer and Ms. Richmond currently serve
as Class I directors (the “Class I Directors”), Messrs. Jenkins, Weiss and Duncan currently serve as Class II directors
(the “Class II Directors”) and Messrs. Kadenacy, Lemoine and Henley currently serve as Class III directors (the “Class
III Directors”). The Class I Directors’ term will expire at the 2023 annual meeting of stockholders; the Class II Directors’
term will expire at the 2021 annual meeting of stockholders; and the Class III Directors’ term will expire at the 2022 annual
meeting of stockholders. At each succeeding annual meeting of the stockholders of the Company, the successors to the class of directors
whose term expires at that meeting will be elected by plurality vote of all votes cast at such meeting to hold office for a term
expiring at the annual meeting of stockholders held in the third year following the year of their election.


 


Preferred Stock


 


Our charter provides
that shares of preferred stock may be issued from time to time in one or more series. Our Board is authorized to fix the voting
rights, if any, designations, powers, preferences, the relative, participating, optional or other special rights and any qualifications,
limitations and restrictions thereof, applicable to the shares of each series. Our Board is able, without stockholder approval,
to issue preferred stock with voting and other rights that could adversely affect the voting power and other rights of the holders
of the common stock and could have anti-takeover effects. The ability of our Board to issue preferred stock without stockholder
approval could have the effect of delaying, deferring or preventing a change of control of the Company or the removal of existing
management.


 


Warrants


 


The warrants are issued
in registered form under the Warrant Agreement between Continental Stock Transfer & Trust Company, as warrant agent, and
us. The Warrant Agreement provides that the terms of the warrants may be amended without the consent of any holder to cure any
ambiguity or correct any defective provision, but requires the approval by the holders of at least a majority of the then outstanding
warrants to make any change that adversely affects the interests of the holders subject to the terms and conditions therein. Additionally,
solely with respect to the private placement warrants, approval by the holders of at least a majority of the then outstanding private
placement warrants is required to make any amendment to the terms of the private placement warrants or any provision of the Warrant
Agreement with respect to the private placement warrants.


 


You should review a
copy of the Warrant Agreement, which we have filed with the SEC, for a complete description of the terms and conditions applicable
to the warrants.


 






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Public Warrants


 


Each public warrant
entitles the registered holder to purchase one share of Class A common stock at a price of $11.50 per share, subject to adjustment
as discussed below, at any time commencing 30 days after the closing of the Atlas Business Combination, provided that the
Company has an effective registration statement under the Securities Act covering the Class A common stock issuable upon exercise
of the warrants and a current prospectus relating thereto is available (or the Company permits holders to exercise their warrants
on a cashless basis under the circumstances specified in the Warrant Agreement) and such shares are registered, qualified or exempt
from registration under the securities, or blue sky, laws of the state of residence of the holder. Pursuant to the Warrant Agreement,
a warrant holder may exercise its warrants only for a whole number of shares of Class A common stock. This means only a whole
warrant may be exercised at a given time by a warrant holder. The warrants will expire five years after the closing of the Atlas
Business Combination, or earlier upon redemption or liquidation.


 


We will not be obligated
to deliver any Class A common stock pursuant to the exercise of a warrant and will have no obligation to settle such warrant
exercise unless a registration statement under the Securities Act with respect to the Class A common stock underlying the
warrants is then effective and a prospectus relating thereto is current, subject to our satisfying our obligations described below
with respect to registration. No warrant will be exercisable and we will not be obligated to issue a share of Class A common
stock upon the exercise of a warrant unless the Class A common stock issuable upon such warrant exercise has been registered,
qualified or deemed to be exempt under the securities laws of the state of residence of the registered holder of the warrants.
In the event that the conditions in the two immediately preceding sentences are not satisfied with respect to a warrant, the holder
of such warrant will not be entitled to exercise such warrant and such warrant may have no value and expire worthless. In no event
will we be required to net cash settle any warrant.


 


Once the warrants become
exercisable, we may call the warrants for redemption:


 


		●	in whole and not in part;



 


		●	at a price of $0.01 per warrant;



 


		●	upon not less than 30 days’ prior written notice
of redemption to each warrant holder; and



 


		●	if, and only if, the reported last sales price of our Class A
common stock equals or exceeds $18.00 per share (as adjusted for share splits, share dividends, reorganizations, recapitalizations
and the like) for any 20 trading days within a 30-trading day period ending on the third business day prior to the date on
which we send the notice of redemption to the warrant holders, provided that there is an effective registration statement covering
the shares of common stock issuable upon exercise of the public warrants, and a current prospectus relating thereto, available
throughout the 30-day redemption period or we have elected to require the exercise of warrants on a “cashless basis”.



 


If and when the warrants
become redeemable, we may exercise our redemption right even if we are unable to register or qualify the underlying securities
for sale under all applicable state securities laws.


 


If the foregoing conditions
are satisfied and we issue a notice of redemption of the warrants, each warrant holder will be entitled to exercise his, her or
its warrant prior to the scheduled redemption date. However, the price of our Class A common stock may fall below the $18.00
redemption trigger price (as adjusted for share splits, share dividends, reorganizations, recapitalizations and the like) as well
as the $11.50 warrant exercise price after the redemption notice is issued.


 


If we call the warrants
for redemption as described above, our management will have the option to require any holder that wishes to exercise his, her or
its warrant to do so on a “cashless basis.” In determining whether to require any holders to exercise their warrants
on a “cashless basis,” management will consider, among other factors, the Company’s cash position, the number
of warrants that are outstanding and the dilutive effect on our shareholders of issuing the maximum number of shares of Class A
common stock issuable upon the exercise of the Company’s warrants. If management takes advantage of this option, all holders
of warrants would pay the exercise price by surrendering their warrants for that number of shares of Class A common stock
equal to the quotient obtained by dividing (x) the product of the number of shares of Class A common stock underlying
the warrants, multiplied by the difference between the exercise price of the warrants and the “fair market value” (defined
below) by (y) the fair market value. The “fair market value” will mean the average reported closing price of one
share of Class A common stock for the 10 trading days ending on the third trading day prior to the date on which the notice
of redemption is sent to the holders of warrants. If management takes advantage of this option, the notice of redemption will contain
the information necessary to calculate the number of shares of Class A common stock to be received upon exercise of the warrants,
including the “fair market value” in such case. Requiring a cashless exercise in this manner will reduce the number
of shares to be issued and thereby lessen the dilutive effect of a warrant redemption. If we call the warrants for redemption and
our management does not take advantage of this option, the holders of the private placement warrants and their permitted transferees
would still be entitled to exercise their private placement warrants for cash or on a cashless basis using the same formula described
above that other warrant holders would have been required to use had all warrant holders been required to exercise their warrants
on a cashless basis, as described in more detail below.


 






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A holder of a warrant
may notify us in writing in the event it elects to be subject to a requirement that such holder will not have the right to exercise
such warrant, to the extent that after giving effect to such exercise, such person (together with such person’s affiliates),
to the warrant agent’s actual knowledge, would beneficially own in excess of 4.9% or 9.8% (as specified by the holder) of
Class A common stock issued and outstanding immediately after giving effect to such exercise.


 


If the number of shares
of outstanding Class A common stock is increased by a share capitalization, a share dividend payable in Class A common
stock, a split-up of common stock or other similar event, then, on the effective date of such share capitalization, dividend,
split-up or similar event, the number of shares of Class A common stock issuable on exercise of each warrant will be
increased in proportion to such increase in the outstanding common stock. A rights offering to holders of common stock entitling
holders to purchase Class A common stock at a price less than the fair market value will be deemed a share dividend of a number
of shares of Class A common stock equal to the product of (i) the number of shares of Class A common stock actually
sold in such rights offering (or issuable under any other equity securities sold in such rights offering that are convertible into
or exercisable for Class A common stock) and (ii) the quotient of (x) the price per share of Class A common
stock paid in such rights offering and (y) the fair market value. For these purposes, (i) if the rights offering is for
securities convertible into or exercisable for Class A common stock, in determining the price payable for Class A common
stock, there will be taken into account any consideration received for such rights, as well as any additional amount payable upon
exercise or conversion and (ii) fair market value means the volume weighted average price of Class A common stock as
reported during the ten (10) trading day period ending on the trading day prior to the first date on which the Class A common
stock trades on the applicable exchange or in the applicable market, regular way, without the right to receive such rights.


 


In addition, if we,
at any time while the warrants are outstanding and unexpired, pay a dividend or make a distribution in cash, securities or other
assets to the holders of Class A common stock on account of such Class A common stock (or other securities into which
the warrants are convertible), other than (a) as described above, (b) certain ordinary cash dividends, then the warrant
exercise price will be decreased, effective immediately after the effective date of such event, by the amount of cash and/or the
fair market value of any securities or other assets paid on each Class A common stock in respect of such event.


 


If the number of outstanding
shares of Class A common stock is decreased by a consolidation, combination, reverse share split or reclassification of the
Class A common stock or other similar event, then, on the effective date of such consolidation, combination, reverse share
split, reclassification or similar event, the number of shares of Class A common stock issuable on exercise of each warrant
will be decreased in proportion to such decrease in outstanding shares of Class A common stock.


 


Whenever the number
of shares of Class A common stock purchasable upon the exercise of the warrants is adjusted, as described above, the warrant
exercise price will be adjusted by multiplying the warrant exercise price immediately prior to such adjustment by a fraction (x) the
numerator of which will be the number of shares of Class A common stock purchasable upon the exercise of the warrants immediately
prior to such adjustment, as applicable, and (y) the denominator of which will be the number of shares of Class A common
stock so purchasable immediately thereafter, as applicable.


 






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In case of any reclassification
or reorganization of the outstanding Class A common stock (other than those described above or that solely affects the par
value of such Class A common stock), or in the case of any merger or consolidation of us with or into another corporation
(other than a consolidation or merger in which we are the continuing corporation and that does not result in any reclassification
or reorganization of our outstanding Class A common stock), or in the case of any sale or conveyance to another corporation
or entity of all or substantially all of the assets or other property of the Company in connection with which we are dissolved,
the holders of the warrants will thereafter have the right to purchase and receive, upon the basis and upon the terms and conditions
specified in the warrants and in lieu of the Class A common stock immediately theretofore purchasable and receivable upon
the exercise of the rights represented thereby, the kind and amount of Class A common stock or other securities or property
(including cash) receivable upon such reclassification, reorganization, merger or consolidation, or upon a dissolution following
any such sale or transfer, that the holder of the warrants would have received if such holder had exercised their warrants immediately
prior to such event. If less than 70% of the consideration receivable by the holders of Class A common stock in such a transaction
is payable in the form of common stock in the successor entity that is listed for trading on a national securities exchange or
is quoted in an established over-the-counter market, or is to be so listed for trading or quoted immediately following such
event, and if the registered holder of the warrant properly exercises the warrant within thirty days following public disclosure
of such transaction, the warrant exercise price will be reduced as specified in the Warrant Agreement based on the Black-Scholes Warrant
Value (as such term is defined in the Warrant Agreement) of the warrant. The purpose of such exercise price reduction is to provide
additional value to holders of the warrants when an extraordinary transaction occurs during the exercise period of the warrants
pursuant to which the holders of the warrants otherwise do not receive the full potential value of the warrants.


 


The warrants may be
exercised upon surrender of the warrant certificate on or prior to the expiration date at the offices of the warrant agent, with
the exercise form on the reverse side of the warrant certificate completed and executed as indicated, accompanied by full payment
of the exercise price (unless on a cashless basis, if applicable), by certified or official bank check payable to us, for the number
of warrants being exercised. The warrant holders do not have the rights or privileges of holders of common stock and any voting
rights until they exercise their warrants and receive Class A common stock. After the issuance of Class A common stock
upon exercise of the warrants, each holder will be entitled to one vote for each Class A common stock held of record on all
matters to be voted on by shareholders.


 


No fractional shares
will be issued upon exercise of the warrants. If, upon exercise of the warrants, a holder would be entitled to receive a fractional
interest in a share, we will, upon exercise, round down to the nearest whole number the number of shares of Class A common
stock to be issued to the warrant holder.


 


Private Placement Warrants


 


The private placement
warrants (including the shares of Class A common stock issuable upon exercise of the private placement warrants) will not
be redeemable by us so long as they are held by Boxwood Sponsor LLC (the “Sponsor”), who initially purchased such warrants,
or its respective permitted transferees. The Sponsor or its respective permitted transferees have the option to exercise the private
placement warrants on a cashless basis. Except as described below, the private placement warrants have terms and provisions that
are identical to those of the public warrants. If any private placement warrants are transferred to holders other than the Sponsor
or its permitted transferees, such warrants will become public warrants under the Warrant Agreement upon such transfer and will
be redeemable by us and exercisable by the holders on the same basis as all other public warrants.


 


If holders of the private
placement warrants elect to exercise them on a cashless basis, they would pay the exercise price by surrendering his, her or its
warrants for that number of shares of Class A common stock equal to the quotient obtained by dividing (x) the product
of the number of shares of Class A common stock underlying the warrants, multiplied by the difference between the exercise
price of the warrants and the “fair market value” (defined below) by (y) the fair market value. The “fair
market value” will mean the average reported closing price of the shares of Class A common stock for the 10 trading
days ending on the third trading day prior to the date on which the notice of warrant exercise is sent to the warrant agent.


 






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Registration Rights


 


Continuing Members Registration Rights Agreement


 


On February 14,
2020, in connection with the consummation of the Atlas Business Combination, the Company entered into a registration rights agreement
(the “Continuing Members RRA”) with Atlas Holdings and its limited partners (the “Continuing Members”).
Under the Continuing Members RRA, the Company has certain obligations to register for resale under the Securities Act all or any
portion of the shares of the Class A common stock that the Continuing Members hold as of the date of the Continuing Members
RRA and that they may acquire thereafter, including upon the exchange or redemption of any other security therefor (collectively,
the “Continuing Member Registrable Securities”).


 


Following the consummation
of the Atlas Business Combination, the Company filed a registration statement registering the resale of the Continuing Member Registrable
Securities. Additionally, Atlas Technical Consultants SPV, LLC and Arrow Environmental SPV LLC (together, “BCP”) may
demand an unlimited number of underwritten offerings for all or part of the Continuing Member Registrable Securities held by BCP
and the other Continuing Members under the Continuing Member RRA.


 


Holders of the Continuing
Member Registrable Securities have certain “piggy-back” registration rights with respect to registration statements.
The company will bear the expenses incurred in connection with the filing of any such registration statements.


 


GSO Registration Rights Agreement


 


In connection with the
consummation of the Atlas Business Combination, we entered into a registration rights agreement (the “GSO RRA”) with
GSO Capital Opportunities Fund III LP and the other holders party thereto (together, “GSO”). Under the GSO RRA, we
have certain obligations to register for resale under the Securities Act all or any portion of the shares of the Class A common
stock that the Continuing Members (as defined in the Amended and Restated Limited Liability Company Agreement of Holdings) hold
as of the date of the GSO RRA and that they may acquire thereafter, including upon the exchange or redemption of any other security
therefor (collectively, the “GSO Registrable Securities”).


 


We have filed a registration
statement registering the resale of the GSO Registrable Securities. Additionally, GSO may demand up to two underwritten offerings
for all or part of the GSO Registrable Securities held by GSO under the GSO RRA.


 


Holders of the GSO Registrable
Securities have certain “piggy-back” registration rights with respect to registration statements and rights to require
us to register for resale the GSO Registrable Securities pursuant to Rule 415 under the Securities Act. We will bear the expenses
incurred in connection with the filing of any such registration statements.


 






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The GSO RRA does not
contemplate the payment of penalties or liquidated damages to GSO as a result of a failure to register, or delays with respect
to the registration of, the GSO Registrable Securities.


 


Boxwood Registration Rights Agreement


 


Pursuant to a registration
rights agreement entered into on November 15, 2018, the holders of shares of Class F common stock (subsequently converted
into Class A common stock in connection with the Atlas Business Combination), private placement units, private placement shares,
private placement warrants and any warrants that may be issued upon conversion of the loans (and their underlying securities) made
by the Sponsor to the Company in connection with the IPO and which were repaid upon the completion of the Atlas Business Combination
(the “Working Capital Loans”) are entitled to registration rights. The holders of these securities are entitled to
make up to three demands (or one demand in the case of private placement securities to be acquired by an affiliate of Macquarie
Capital (USA) Inc. (“Macquarie Capital”)), excluding short form registration demands, that we register such securities
for sale under the Securities Act. In addition, these holders have “piggy-back” registration rights to include such
securities in other registration statements filed by us and rights to require us to register for resale such securities pursuant
to Rule 415 under the Securities Act. However, the registration rights agreement provides that we will not permit any registration
statement filed under the Securities Act to become effective until termination of the applicable lock-up period. In the case
of the private placement securities acquired by an affiliate of Macquarie Capital, the demand registration right provided is not
exercisable for longer than five years from the effective date of the registration statement of the IPO in compliance with FINRA
Rule 5110(f)(2)(G)(iv) and the piggy-back registration right provided is not exercisable for longer than seven years
from the effective date of the registration statement of the IPO in compliance with FINRA Rule 5110(f)(2)(G)(v). We will bear
the expenses incurred in connection with the filing of any such registration statements. The registration rights agreement does
not contemplate the payment of penalties or liquidated damages to the stockholders party thereto as a result of a failure to register,
or delays with respect to the registration of, our securities.


 


Transfer Agent and Registrar


 


The transfer agent and
registrar for our common stock and warrants is Continental Stock Transfer & Trust Company.


 


Listing of Securities


 


Our Class A common
stock is listed on the Nasdaq under the symbol “ATCX.” Our warrants were previously listed on the Nasdaq under the
symbol “ATCXW.” In November 2020, all warrants were exchanged for Class A common stock, and on December 2, 2020, Nasdaq
filed a Form 25 to deregister the warrants from the exchange.


 


 


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