Document:

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                                                                     EXHIBIT 4.6

NEITHER THIS WARRANT NOR THE SECURITIES FOR WHICH IT IS EXERCISABLE HAVE BEEN
REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED (THE
"SECURITIES ACT"), OR ANY APPLICABLE STATE SECURITIES LAWS, AND MAY NOT BE SOLD,
OFFERED FOR SALE, PLEDGED OR HYPOTHECATED OR OTHERWISE TRANSFERRED IN THE
ABSENCE OF A REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO SUCH SECURITIES
UNDER THE SECURITIES ACT OR AN EXEMPTION FROM THE SECURITIES ACT. ANY SUCH
TRANSFER MAY ALSO BE SUBJECT TO COMPLIANCE WITH APPLICABLE STATE SECURITIES LAWS
AND THE LAWS OF OTHER APPLICABLE JURISDICTIONS.

THIS WARRANT AND THE SHARES OF COMMON STOCK ISSUABLE UPON EXERCISE HEREOF ARE
SUBJECT TO THE TERMS OF THIS CLASS C WARRANT, COPIES OF WHICH ARE AVAILABLE FROM
NEPHROS, INC., INCLUDING, WITHOUT LIMITATION, THE LOCK-UP PROVISIONS OF SECTION
12 HEREOF.

                                  NEPHROS, INC.

                                     Form of

                  Class C Warrant for the Purchase of Shares of
                                  Common Stock

No. C-2                                                       September 22, 2003

                FOR VALUE RECEIVED, NEPHROS, INC., a Delaware corporation (the
"Company"), hereby certifies that George Hatsopoulos or his registered assigns
(the "Holder") is entitled to purchase from the Company, subject to the
provisions of this Warrant (the "Warrant"), at any time on or after the date
hereof (the "Initial Exercise Date"), and prior to 11:59 P.M., New York City
time, on September 11, 2006 (the "Termination Date"), 3,907 fully paid and
non-assessable shares of the Common Stock, $.001 par value, of the Company
("Common Stock"), at an exercise price of $2.50 per share of Common Stock for an
aggregate exercise price of nine thousand seven hundred sixty-seven dollars and
fifty cents ($9,767.50) (the aggregate purchase price payable for the Warrant
Shares hereunder is hereinafter sometimes referred to as the "Aggregate Exercise
Price"). The number of shares of Common Stock to be received upon exercise of
this Warrant and the price to be paid for each share of Common Stock are subject
to possible adjustment from time to time as hereinafter set forth. The shares of
Common Stock or other securities or property deliverable upon such exercise as
adjusted from time to time is hereinafter sometimes referred to as the "Warrant
Shares." The exercise price of a share of Common Stock in effect at any time and
as adjusted from time to time is hereinafter sometimes referred to as the "Per
Share Exercise Price." The Per Share Exercise Price is

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subject to adjustment as hereinafter provided; in the event of any such
adjustment, the number of Warrant Shares shall also be adjusted, by dividing the
Aggregate Exercise Price by the Per Share Exercise Price in effect immediately
after such adjustment. The Aggregate Exercise Price is not subject to adjustment
except to the extent of any partial exercise of this Warrant. This Warrant may
constitute one in a series of warrants (the "Class C Warrants") which includes
this Warrant and any other Class C Warrant for the Purchase of Shares of Common
Stock of the Company, of like tenor hereto.

                1.      Exercise of Warrant.

                (a)     This Warrant may be exercised in whole or in part, at
any time by its holder commencing on the Initial Exercise Date and prior to the
Termination Date:

                        (i)     by presentation and surrender of this Warrant,
        together with the duly executed subscription form attached at the end
        hereof, at the address set forth in Subsection 8(a) hereof, together
        with payment, by certified or official bank check or wire transfer
        payable to the order of the Company, of the Aggregate Exercise Price or
        the proportionate part thereof if exercised in part; or

                        (ii)    by presentation and surrender of this Warrant,
        together with the duly executed cashless exercise form attached at the
        end hereof (a "Cashless Exercise") at the address set forth in
        Subsection 8(a) hereof. The exchange of Common Stock for the Warrant
        shall take place on the date specified in the Cashless Exercise Form or,
        if later, the date the Cashless Exercise Form is surrendered to the
        Company (the "Exchange Date"). Such presentation and surrender shall be
        deemed a waiver of the Holder's obligation to pay the Aggregate Exercise
        Price, or the proportionate part thereof if this Warrant is exercised in
        part. In the event of a Cashless Exercise, this Warrant shall represent
        the right to subscribe for and to acquire the number of shares of Common
        Stock equal to (x) the number of shares of Common Stock specified by the
        Holder in its Cashless Exercise Form (the "Total Number") (such number
        not to exceed the maximum number of shares of Common Stock subject to
        this Warrant, as may be adjusted from time to time) less (y) the number
        of shares of Common Stock equal to the quotient obtained by dividing (A)
        the product of the Total Number and the existing Per Share Exercise
        Price by (B) the fair market value per share of Common Stock at such
        time, as determined by the Board of Directors of the Company in good
        faith (the "Per Share FMV"). No Cashless Exercise shall be effected
        unless the Per Share FMV is greater than the Per Share Exercise Price as
        of the Exchange Date.

                (b)     If this Warrant is exercised in part only, the Company
shall, upon presentation of this Warrant upon such exercise, execute and deliver
(along with the certificate for the Warrant Shares purchased) a new Warrant
evidencing the rights of the Holder hereof to purchase the balance of the
Warrant Shares purchasable hereunder upon the same terms and conditions as
herein set forth. Upon proper exercise of this Warrant, the Company promptly
shall deliver certificates for the Warrant Shares to the Holder duly legended as
authorized by the subscription form. No fractional shares or scrip representing
fractional shares shall be issued upon exercise of this Warrant; provided that
the Company shall pay to the Holder of the Warrant cash in lieu of such
fractional shares.

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                2.      Reservation of Warrant Shares; Fully Paid Shares; Taxes.
The Company hereby represents that it has, and until expiration of this Warrant
agrees that it shall, reserve for issuance or delivery upon exercise of this
Warrant, such number of shares of the Common Stock as shall be required for
issuance and/or delivery upon exercise of this Warrant in full, and agrees that
all Warrant Shares so issued and/or delivered will be validly issued, fully paid
and non-assessable, and further agrees to pay all taxes (other than income
taxes) and charges that may be imposed upon such issuance and/or delivery. The
Company shall not, however, be required to pay any tax which may be payable in
respect of any transfer involved in the issue or delivery of Common Stock (or
other securities or assets) in a name other than that in which the Warrants so
exercised were registered, and no such issue or delivery shall be made unless
and until the person requesting such issue has paid to the Company the amount of
such tax or has established, to the satisfaction of the Company, that such tax
has been paid.

                3.      Protection Against Dilution.

                (a)     In case the Company shall hereafter (i) pay a dividend
or make a distribution on its capital stock in shares of Common Stock, (ii)
subdivide its outstanding shares of Common Stock into a greater number of
shares, (iii) combine its outstanding shares of Common Stock into a smaller
number of shares or (iv) issue by reclassification of its Common Stock any
shares of capital stock of the Company (each of (i) through (iv) an "Action"),
the Per Share Exercise Price shall be adjusted to be equal to a fraction, the
numerator of which shall be the Aggregate Exercise Price and the denominator of
which shall be the number of shares of Common Stock or other capital stock of
the Company that the Holder would have held (solely as a result of the exercise
of this Warrant and the operation of such Action) immediately following such
Action if this Warrant had been exercised immediately prior to such Action. An
adjustment made pursuant to this Subsection 3(b) shall become effective
immediately after the record date in the case of a dividend or distribution and
shall become effective immediately after the effective date in the case of a
subdivision, combination or reclassification.

                (b)     In the event of any capital reorganization or
reclassification not otherwise covered in this Section 3, or any consolidation
or merger to which the Company is a party other than a merger or consolidation
in which the Company is the continuing corporation, or in case of any sale or
conveyance to another entity of the property of the Company as an entirety or
substantially as an entirety, or in the case of any statutory exchange of
securities with another corporation (including any exchange effected in
connection with a merger of a third corporation into the Company), the Holder of
this Warrant shall have the right thereafter to receive on the exercise of this
Warrant the kind and amount of securities, cash or other property which the
Holder would have owned or have been entitled to receive immediately after such
reorganization, reclassification, consolidation, merger, statutory exchange,
sale or conveyance had this Warrant been exercised immediately prior to the
effective date of such reorganization, reclassification, consolidation, merger,
statutory exchange, sale or conveyance and in any such case, if necessary,
appropriate adjustment shall be made in the application of the provisions set
forth in this Section 3 with respect to the rights and interests thereafter of
the Holder of this Warrant to the end that the provisions set forth in this
Section 3 shall thereafter correspondingly be made applicable, as nearly as may
reasonably be, in relation to any shares of stock or other securities or
property thereafter deliverable on the exercise of this Warrant. The above

                                      - 3 -

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provisions of this Subsection 3(b) shall similarly apply to successive
reorganizations, reclassifications, consolidations, mergers, statutory
exchanges, sales or conveyances.

                (c)     Whenever the Per Share Exercise Price payable upon
exercise of this Warrant is adjusted pursuant to this Section 3, the number of
shares of Common Stock underlying this Warrant shall simultaneously be adjusted
to equal the number obtained by dividing the Aggregate Exercise Price (as the
same shall be reduced to the extent of any partial exercise of this Warrant) by
the adjusted Per Share Exercise Price.

                (d)     If, as a result of an adjustment made pursuant to this
Section 3, the Holder shall become entitled to receive, upon exercise of the
Warrant, shares of two or more classes of capital stock or shares of Common
Stock and other capital stock of the Company, the Board of Directors (whose
determination shall be conclusive) shall determine the allocation of the
adjusted Per Share Exercise Price between or among shares or such classes of
capital stock or shares of Common Stock and other capital stock.

                4.      Limited Transferability. This Warrant may not be sold,
transferred, assigned or hypothecated by the Holder except in compliance with
the provisions of the Act and the applicable state securities "blue sky" laws,
and is so transferable only upon the books of the Company which it shall cause
to be maintained for such purpose. The Company may treat the registered Holder
of this Warrant as he or it appears on the Company's books at any time as the
Holder for all purposes.

                5.      Loss, etc., of Warrant. Upon receipt of evidence
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant, and of indemnity reasonably satisfactory to the Company (which may
include a bond), if lost, stolen or destroyed, and upon surrender and
cancellation of this Warrant, if mutilated, the Company shall execute and
deliver to the Holder a new Warrant of like date, tenor and denomination.

                6.      Investment Intent.

                (a)     The Holder represents, by accepting this Warrant, that
it understands that this Warrant and any securities obtainable upon exercise of
this Warrant have not been registered for sale under Federal or state securities
laws and are being offered and sold to the Holder pursuant to one or more
exemptions from the registration requirements of such securities laws. The
Holder is an "accredited investor" within the meaning of Regulation D under the
Securities Act of 1933, as amended (the "Act"). In the absence of an effective
registration of such securities or an exemption therefrom, any certificates for
such securities shall bear the legend set forth on the first page hereof. The
Holder understands that it must bear the economic risk of its investment in this
Warrant and any securities obtainable upon exercise of this Warrant for an
indefinite period of time, as this Warrant and such securities have not been
registered under Federal or state securities laws and therefore cannot be sold
unless subsequently registered under such laws, unless as exemption from such
registration is available.

                (b)     The Holder, by its acceptance of its Warrant, represents
and warrants to the Company that it has sufficient knowledge and experience in
financial and business matters to be capable of evaluating the merits and risks
of the prospective investment in Warrant Shares

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and of making an informed investment decision with respect thereto. The Holder
acknowledges that any disclosure materials it has received from the Company may
not contain all information that is necessary to make an investment decision
with respect to the Company and the Warrant Shares and that it must rely on its
own examination of the Company and the terms and conditions of this Warrant
prior to making any investment decision with respect to the Warrant Shares. The
Holder further represents and warrants that it has been afforded full
opportunity to ask questions and obtain copies of all relevant documents
concerning the Company and the Warrant Shares, and all of its questions and
requests for documents and information have been answered to its complete
satisfaction.

                (c)     The Holder, by its acceptance of its Warrant, represents
to the Company that it is acquiring this Warrant and will acquire any securities
obtainable upon exercise of this Warrant for its own account for investment and
not with a view to, or for sale in connection with, any distribution thereof in
violation of the Act. The Holder agrees that this Warrant and any such
securities will not be sold or otherwise transferred unless (i) a registration
statement with respect to such transfer is effective under the Act and any
applicable state securities laws or (ii) such sale or transfer is made pursuant
to one or more exemptions from the Act.

                7.      Status of Holder. This Warrant does not confer upon the
Holder any right to vote or to consent to or receive notice as a stockholder of
the Company, as such, in respect of any matters whatsoever, or any other rights
or liabilities as a stockholder, prior to the exercise hereof.

                8.      Notices. No notice or other communication under this
Warrant shall be effective unless, but any notice or other communication shall
be effective and shall be deemed to have been given if, the same is in writing
and is mailed by first-class mail, postage prepaid, addressed to:

                (a)     the Company c/o Audubon Business and Technology Center,
        Columbia-Presbyterian Medical Center, 3960 Broadway, 4th Floor, New
        York, NY 10032, Attention: President, or such other address as the
        Company has designated by notice to the Holder; or

                (b)     the Holder at Pharos, Inc., 85 First Avenue, Waltham,
        Massachusetts 02254, or such other address as the Holder has designated
        by notice to the Company.

                9.      Headings. The headings of this Warrant have been
inserted as a matter of convenience and shall not affect the construction
hereof.

                10.     Applicable Law. This Warrant shall be governed by and
construed in accordance with the law of the State of New York without giving
effect to principles of conflicts of law thereof.

                11.     Amendments. This Warrant may be amended only by mutual
written agreement of the Company and the holder or holders holding Class C
Warrants exercisable for a majority of the shares of Common Stock issuable upon
exercise of all then-outstanding Class C Warrants (the "Majority Holders"), and
the Company may take any action herein prohibited or omit to take any action
herein required to be performed by it, and any breach of any covenant,

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agreement, warranty or representation may be waived, only if the Company has
obtained the written consent or waiver of the Majority Holders.

                12.     Lock-up. (a) General Lock-up. If the Company shall
effect a primary or a secondary public offering of its securities or if at any
time, the Company shall register its shares of Common Stock under the Securities
Act for sale to the public, the holder or holders of Common Stock issued or
issuable upon exercise of this Warrant shall not sell publicly, make any short
sale of, grant any option for the purchase of, or otherwise dispose publicly of,
any shares of Common Stock without the prior written consent of the Company
during the period beginning ten (10) days prior to the effectiveness of the
registration statement pursuant to which such public offering shall be made and
ending on the date 180 days after the effective date of such registration
statement. By acceptance of this Warrant, or the shares of Common Stock issued
or issuable upon exercise hereof, the holder hereof or thereof agrees to be
bound by the terms of this Section 12.

                        (b)     Special IPO Lock-up. In the event of an initial
public offering (the "IPO") of Common Stock (whether such IPO occurs prior to or
after the issuance hereof), the Holder, during the period commencing seven days
prior to the date of the final prospectus relating to the IPO and ending 360
days thereafter (the "Restricted Period"):

                        (i)     agrees not to (x) offer, pledge, sell, contract
        to sell, sell any option or contract to purchase, purchase any option or
        contract to sell, grant any option, right or warrant to purchase, or
        establish or increase a put equivalent position or liquidate or decrease
        a call equivalent position within the meaning of Section 16 of the
        Securities Exchange Act of 1934, as amended, and the rules and
        regulations promulgated thereunder or otherwise transfer or dispose of,
        directly or indirectly, any shares of Common Stock or other capital
        stock of the Company or any securities convertible into or exercisable
        or exchangeable for any shares of Common Stock or other capital stock of
        the Company (collectively, the "Securities") or (y) enter into any swap
        or other arrangement that transfers all or a portion of the economic
        consequences associated with the ownership of any Securities of the
        Company, or publicly announce an intention to effect any such
        transaction (regardless of whether any of the transactions described in
        clause (x) or (y) is to be settled by the delivery of Common Stock, or
        such other Securities, in cash or otherwise), without the prior written
        consent of the lead underwriter for such IPO (the "Underwriter");

                        (ii)    authorizes the Company to cause the transfer
        agent to decline to transfer and/or to note stop transfer restrictions
        on the transfer books and records of the Company with respect to any
        Securities for which the Holder is the record holder and, in the case of
        any such Securities for which the Holder is the beneficial but not the
        record holder, agrees to cause the record holder to authorize the
        Company to cause the transfer agent to decline to transfer and/or to
        note stop transfer restrictions on such books and records with respect
        to such Securities; and

                        (iii)   agrees that the restrictions set forth in this
        Section 12(b) shall apply (A) for 450 days with respect to any
        transaction involving any Securities in excess of one-third (1/3) of the
        Securities held by the Holder on the date of the final prospectus,

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        and (B) for 540 days with respect to any transaction involving any
        Securities in excess of two-thirds (2/3) of the Securities held by the
        Holder on the date of the final prospectus.

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                IN WITNESS WHEREOF, the undersigned, acting for and on behalf of
the Company, has executed this Warrant as of the date first written above.

                                     NEPHROS, INC.

                                     By:  /s/ Norman Barta
                                          ----------------------
                                          Name:  Norman Barta
                                          Title: President and Chief Executive
                                                 Officer

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                                  SUBSCRIPTION

                The undersigned, ____________________________, pursuant to the
provisions of the foregoing Warrant, hereby elects to exercise the within
Warrant to the extent of purchasing _____________________ shares of Common Stock
thereunder and hereby makes payment of $_______________ by certified or official
bank check in payment of the exercise price therefor.

Dated:                                  Signature:
      -----------------                           ---------------------------
                                        Address:
                                                ------------------------------

                                CASHLESS EXERCISE

                The undersigned, ____________________________, pursuant to the
provisions of the foregoing Warrant, hereby elects to exchange the within
Warrant for up to ______________ shares of Common Stock of Nephros, Inc.
pursuant to the cashless exercise provisions of the Warrant. The undersigned
hereby confirms the representations, warranties and covenants made by it in the
Warrant.

Dated:                                  Signature:
      -----------------                           ---------------------------
                                        Address:
                                                ------------------------------

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                                   ASSIGNMENT

                FOR VALUE RECEIVED _______________________________________
hereby sells, assigns and transfers unto _____________________________________
the foregoing Warrant and all rights evidenced thereby, and does irrevocably
constitute and appoint _____________________________, attorney, to transfer said
Warrant on the books of Nephros, Inc.

Dated:                                  Signature:
      -----------------                           ---------------------------
                                        Address:
                                                -----------------------------

                               PARTIAL ASSIGNMENT

                FOR VALUE RECEIVED __________________________ hereby assigns and
transfers unto _________________________ the right to purchase __________ shares
of the Common Stock, $.001 par value per share, of Nephros, Inc. covered by the
foregoing Warrant, and a proportionate part of said Warrant and the rights
evidenced thereby, and does irrevocably constitute and appoint
__________________________, attorney, to transfer that part of said Warrant on
the books of Nephros, Inc.

Dated:                                  Signature:
      -----------------                           ---------------------------
                                        Address:
                                                 ----------------------------

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                                                                    Exhibit 4.7

       This Warrant was originally issued on June 19, 2002. THESE SECURITIES
       HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 OR ANY
       APPLICABLE STATE SECURITIES LAWS. THEY MAY NOT BE SOLD, OFFERED FOR
       SALE, PLEDGED OR HYPOTHECATED OR OTHERWISE TRANSFERRED IN THE ABSENCE OF
       A REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO THE SECURITIES UNDER
       SUCH ACT OR AN EXEMPTION THEREFROM. ANY SUCH TRANSFER MAY ALSO BE
       SUBJECT TO APPLICABLE STATE SECURITIES LAWS.

                                 NEPHROS, INC.

                            STOCK PURCHASE WARRANT
                            ----------------------

           Date of Issuance: June 19, 2002        Certificate No. W-1

   FOR VALUE RECEIVED, Nephros, Inc., a Delaware corporation (the "Company"),
hereby grants to Plexus Services Corp. or its permitted assigns (the
"Registered Holder") the right to purchase from the Company 600,000 shares of
the Company's Common Stock at a price per share of $3.00 (as adjusted from time
to time hereunder, the "Exercise Price"). Certain capitalized terms used herein
are defined in Section 4 hereof. The amount and kind of securities obtainable
pursuant to the rights granted hereunder and the purchase price for such
securities are subject to adjustment pursuant to the provisions contained in
this Warrant.

   This Warrant is subject to the following provisions:

   Section 1. Exercise of Warrant.
              -------------------

   1A. Exercise Period. The Registered Holder may exercise, in whole or in part
       ---------------
(but not as to a fractional share of Common Stock), the purchase rights
represented by this Warrant at any time and from time to time after the Date of
Issuance to and including the fifth anniversary thereof (the "Exercise Period").

   1B. Exercise Procedure.

      (i) This Warrant shall be deemed to have been exercised when the Company
   has received all of the following items (the "Exercise Time"):

          (a) a completed Exercise Agreement, as described in paragraph 1C
       below, executed by the Person exercising all or part of the purchase
       rights represented by this Warrant (the "Purchaser");

          (b) this Warrant; and

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          (c) a certified check payable to the Company in an amount equal to
       the product of the Exercise Price multiplied by the number of shares of
       Common Stock being purchased upon such exercise (the "Aggregate Exercise
       Price").

      (ii) Certificates for shares of Common Stock purchased upon exercise of
   this Warrant shall be delivered by the Company to the Purchaser within
   twenty business days after the date of the Exercise Time. Unless this
   Warrant has expired or all of the purchase rights represented hereby have
   been exercised, the Company shall prepare a new Warrant, substantially
   identical hereto, representing the rights formerly represented by this
   Warrant which have not expired or been exercised and shall within such
   twenty-day period, deliver such new Warrant to the Person designated for
   delivery in the Exercise Agreement.

      (iii) The Common Stock issuable upon the exercise of this Warrant shall
   be deemed to have been issued to the Purchaser at the Exercise Time, and the
   Purchaser shall be deemed for all purposes to have become the record holder
   of such Common Stock at the Exercise Time.

      (iv) The issuance of certificates for shares of Common Stock upon
   exercise of this Warrant shall be made without charge to the Registered
   Holder for any issuance tax in respect thereof or other cost incurred by the
   Company in connection with such exercise and the related issuance of shares
   of Common Stock. Each share of Common Stock issuable upon exercise of this
   Warrant shall upon payment of the Exercise Price therefor, be fully paid and
   nonassessable and free from all liens and charges, with respect to the
   issuance thereof, created by the Company.

      (v) The Company shall not close its books against the transfer of this
   Warrant or of any share of Common Stock issued or issuable upon the exercise
   of this Warrant in any manner which interferes with the timely exercise of
   this Warrant. The Company shall from time to time take all such action as
   may be necessary to assure that the par value per share of the unissued
   Common Stock acquirable upon exercise of this Warrant is at all times equal
   to or less than the Exercise Price then in effect.

      (vi) The Company shall assist and cooperate with any Registered Holder or
   Purchaser required to make any governmental filings or obtain any
   governmental approvals prior to or in connection with any exercise of this
   Warrant (including, without limitation, making any filings required to be
   made by the Company).

      (vii) Notwithstanding any other provision hereof, if an exercise of any
   portion of this Warrant is to be made in connection with a registered public
   offering or the sale of the Company, the exercise of any portion of this
   Warrant may, at the election of the holder hereof, be conditioned upon the
   consummation of the public offering or sale of the Company in which case
   such exercise shall not be deemed to be effective until the consummation of
   such transaction.

      (viii) The Company shall at all times reserve and keep available out of
   its authorized but unissued shares of Common Stock solely for the purpose of
   issuance upon the exercise of the Warrants, such number of shares of Common
   Stock issuable upon the exercise of all outstanding Warrants. All shares of
   Common Stock which are so issuable shall, when issued, be duly and validly
   issued, fully paid and nonassessable and free from all taxes, liens and
   charges created by the Company. The Company shall take all such actions as
   may be necessary to assure

                                     - 2 -

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   that all such shares of Common Stock may be so issued without violation of
   any applicable law or governmental regulation or any requirements of any
   domestic securities exchange upon which shares of Common Stock may be listed
   (except for official notice of issuance which shall be immediately delivered
   by the Company upon each such issuance). The Company shall not take any
   action which would cause the number of authorized but unissued shares of
   Common Stock to be less than the number of such shares required to be
   reserved hereunder for issuance upon exercise of the Warrants.

   1C. Exercise Agreement. The Registered Holder shall exercise this Warrant by
       ------------------
executing and delivering to the Company the Exercise Agreement substantially in
the form set forth in Exhibit I hereto, except that if, with the prior written
consent of the Company, the shares of Common Stock are not to be issued in the
name of the Person in whose name this Warrant is registered, the Exercise
Agreement shall also state the name of the Person to whom the certificates for
the shares of Common Stock are to be issued. Such Exercise Agreement shall be
dated the actual date of execution thereof.

   1D. Fractional Shares. No fractional shares of Common Stock shall be issued
       -----------------
upon any exercise of Warrants. If more than one Warrant Certificate shall be
delivered for exercise at one time by the same holder, the number of full
shares or securities that shall be issuable upon exercise shall be computed on
the basis of the aggregate number of Warrants exercised. If a fractional share
of Common Stock would, but for the provisions of paragraph 1A and this
paragraph 1D, be issuable upon exercise of the rights represented by this
Warrant, the Company shall, within five business days after the date of the
Exercise Time, deliver to the Purchaser a check payable to the Purchaser in
lieu of such fractional share in an amount equal to the difference between
Market Price of such fractional share as of the date of the Exercise Time and
the Exercise Price of such fractional share.

   1E. Securities Law Provisions.
       -------------------------

      (i) Except as otherwise permitted by this Section 1E, each certificate
   representing shares of Common Stock issued upon the exercise of a Warrant,
   and each certificate issued upon the transfer of any such Common Stock,
   shall be stamped or otherwise imprinted with a legend in substantially the
   following form:

          "The shares represented by this certificate have not been registered
       under the Securities Act of 1933, as amended (the "Act"), or any other
       securities laws and may not be transferred, sold or otherwise disposed
       of in the absence of such registration or an exemption therefrom under
       such Act or other laws."

      (ii) Prior to any transfer of any Warrant that is not registered under an
   effective registration statement under the Securities Act of 1933, as
   amended (the "Securities Act"), the Registered Holder will give written
   notice to the Company of such Registered Holder's intention to effect such
   transfer and to comply in all other respects with this Section 1E. Each such
   notice (i) shall describe the manner and circumstances of the proposed
   transfer in sufficient detail to enable counsel to render the opinions
   referred to below, and (ii) shall designate counsel for the Registered
   Holder giving such notice. The Registered Holder giving such notice will
   submit a copy thereof to the counsel designated in such notice, which
   counsel shall be experienced in securities law matters and the Company will
   promptly submit a copy thereof to its counsel.

                                     - 3 -

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   If in the opinion of both such counsel the proposed transfer may be effected
without registration under the Securities Act, such Registered Holder shall
thereupon be entitled to transfer such securities in accordance with the terms
of the notice delivered by such Registered Holder to the Company. Each Warrant
issued upon or in connection with such transfer shall bear the legend set forth
on the first page of this Warrant.

   If in the opinion of either or both such counsel the proposed transfer may
not legally be effected without registration of such Warrants under the
Securities Act (such opinions to state the basis of the legal conclusions
reached therein), the Company will promptly so notify the Registered Holder
thereof and thereafter such Registered Holder shall not be entitled to transfer
such Warrants until either (x) receipt by the Company of a further notice from
such Registered Holder pursuant to the foregoing provisions of this Section 1E
and fulfillment of the provisions of this Section 1E or (y) such Warrants have
been registered pursuant to an effective registration statement under the Act.
Notwithstanding the foregoing, the Company shall have no obligation to register
any Warrants or, except as stated in the Settlement Agreement and Mutual
Release between Plexus Services Corp. and the Company dated the date hereof,
shares.

   Section 2. Adjustment of Exercise Price and Number of Shares. In order to
              -------------------------------------------------
prevent dilution of the rights granted under this Warrant, the Exercise Price
shall be subject to adjustment from time to time as provided in this Section 2,
and the number of shares of Common Stock obtainable upon exercise of this
Warrant shall be subject to adjustment from time to time as provided in this
Section 2.

   2A. Subdivision or Combination of Common Stock. If the Company at any time
       ------------------------------------------
subdivides (by any stock split, stock dividend, recapitalization or otherwise)
its outstanding shares of Common Stock into a greater number of shares, the
Exercise Price in effect immediately prior to such subdivision shall be
proportionately reduced and the number of shares of Common Stock obtainable
upon exercise of this Warrant shall be proportionately increased. If the
Company at any time combines (by reverse stock split or otherwise) its
outstanding shares of Common Stock into a smaller number of shares, the
Exercise Price in effect immediately prior to such combination shall be
proportionately increased and the number of shares of Common Stock obtainable
upon exercise of this Warrant shall be proportionately decreased.

   2B. Reorganization, Reclassification, Consolidation, Merger or Sale. Any
       ---------------------------------------------------------------
recapitalization (other than as provided in Section 2A above), reorganization,
consolidation, merger, sale of all or substantially all of the Company's assets
or other transaction, in each case which is effected in such a way that the all
outstanding Common Stock is exchanged in whole or in part for other stock,
securities or assets is referred to herein as "Organic Change." Prior to the
consummation of any Organic Change, the Company shall make appropriate
provision to insure that the Registered Holders of the Warrants shall
thereafter have the right to acquire and receive, in lieu of the shares of
Common Stock immediately theretofore acquirable and receivable upon the
exercise of such holder's Warrant, the securities, cash and other assets to
which the holder of the number of shares of Common Stock purchasable (at the
time of such consolidation, merger or sale) upon the exercise of the Warrants
would have been entitled upon such Organic Change. In any such case, the
Company shall make appropriate provision with respect to such holder's rights
and interests to insure that the provisions of this Section 2 and Section 4
shall thereafter be applicable to the Warrants. The Company shall not effect
any such consolidation, merger or sale in which the Company is not the
surviving or successor entity, unless prior to the consummation thereof, the
successor entity resulting from such consolidation or merger or the entity
purchasing such assets assumes by written instrument (in form and substance
reasonably satisfactory to the

                                     - 4 -

<PAGE>

Registered Holder), the obligation to deliver to the Registered Holder such
shares of stock, securities or assets as, in accordance with the foregoing
provisions, such holder may be entitled to acquire.

   2C. Notices.
       -------

      (i) Upon any adjustment of the Exercise Price, the Company shall give
   written notice thereof to the Registered Holder, setting forth in reasonable
   detail the calculation of such adjustment. Failure to give such notice shall
   not affect the validity of the adjustment.

      (ii) The Company shall give written notice to the Registered Holder at
   least 20 days prior to the date on which the Company closes its books or
   takes a record (A) with respect to any dividend or distribution upon the
   Common Stock or (B) with respect to any pro rata subscription offer to
   holders of Common Stock.

   Section 3. Lock-up. By its acceptance of this Warrant, each Registered
              -------
Holder agrees not to, effect any sale or other transfer of equity securities of
Nephros, or any securities convertible into or exchangeable or exercisable for
such securities, during the seven days prior to and the 360 day period
beginning on the effective date of the Company's initial public offering or the
180 day period beginning on the effective date of any other underwritten public
offering (except as part of such underwritten registration), unless (x) senior
management of Nephros is bound by a less burdensome lockup restriction, in
which case the Registered Holder will be bound by the same restrictions
applicable to management or (y) the underwriters managing such underwritten
registration otherwise agree in writing.

   Section 4. Liquidating Dividends. If the Company declares or pays a dividend
              ---------------------
upon the Common Stock payable otherwise than in cash out of earnings or earned
surplus (determined in accordance with generally accepted accounting
principles, consistently applied) except for a stock dividend payable in shares
of Common Stock (a "Liquidating Dividend"), then the Company shall pay to the
Registered Holder of this Warrant at the time of payment thereof the
Liquidating Dividend which would have been paid to such Registered Holder on
the Common Stock had this Warrant been fully exercised immediately prior to the
date on which a record is taken for such Liquidating Dividend, or, if no record
is taken, the date as of which the record holders of Common Stock entitled to
such dividends are to be determined.

   Section 5. Definitions. The following terms have meanings set forth below:
              -----------

   "Common Stock" means the Company's Common Stock.
    ------------

   "Market Price" means as to any security the average of the closing prices of
    ------------
such security's sales on all domestic securities exchanges on which such
security may at the time be listed, or, if there have been no sales on any such
exchange on any day, the average of the highest bid and lowest asked prices on
all such exchanges at the end of such day, or, if on any day such security is
not so listed, the average of the representative bid and asked prices quoted in
the NASDAQ System as of 4:00 P.M., New York time, on such day, or, if on any
day such security is not quoted in the NASDAQ System, the average of the
highest bid and lowest asked prices on such day in the domestic
over-the-counter market as reported by the National Quotation Bureau,
Incorporated, or any similar successor organization, in each such case averaged
over a period of 21 days consisting of the day as of which "Market Price" is
being determined and the 20 consecutive business days prior to such day;
provided that if such security

                                     - 5 -

<PAGE>

is listed on any domestic securities exchange the term "business days" as used
in this sentence means business days on which such exchange is open for
trading. If at any time such security is not listed on any domestic securities
exchange or quoted in the NASDAQ System or the domestic over-the-counter
market, the "Market Price" shall be the fair value thereof determined in good
faith by the Board of Directors of the Company.

   "Person" means an individual, a partnership, a joint venture, a corporation,
    ------
a limited liability company, a trust, an unincorporated organization and a
government or any department or agency thereof.

   Section 6. No Voting Rights; Limitations of Liability. This Warrant shall
              ------------------------------------------
not entitle the holder hereof to any voting rights or other rights as a
stockholder of the Company. No provision hereof, in the absence of affirmative
action by the Registered Holder to purchase Common Stock, and no enumeration
herein of the rights or privileges of the Registered Holder shall give rise to
any liability of such holder for the Exercise Price of Common Stock acquirable
by exercise hereof or as a stockholder of the Company.

   Section 7. Transfers. Neither this Warrant nor any rights hereunder are
              ---------
transferable, in whole or in part, unless the Registered Holder has complied
with the transfer conditions referred to in the legend endorsed hereon and in
Section 1 hereof.

   Section 8. Warrant Exchangeable for Different Denominations. This Warrant is
              ------------------------------------------------
exchangeable, upon the surrender hereof by the Registered Holder at the
principal office of the Company, for new Warrants of like tenor representing in
the aggregate the purchase rights hereunder, and each of such new Warrants
shall represent such portion of such rights as is designated by the Registered
Holder at the time of such surrender. The date the Company initially issues
this Warrant shall be deemed to be the "Date of Issuance" hereof regardless of
the number of times new certificates representing the unexpired and unexercised
rights formerly represented by this Warrant shall be issued. All Warrants
representing portions of the rights hereunder are referred to herein as the
"Warrants."

   Section 9. Replacement. Upon receipt of evidence reasonably satisfactory to
              -----------
the Company (an affidavit of the Registered Holder shall be satisfactory) of
the ownership and the loss, theft, destruction or mutilation of any certificate
evidencing this Warrant, and in the case of any such loss, theft or
destruction, upon receipt of indemnity reasonably satisfactory to the Company,
or, in the case of any such mutilation upon surrender of such certificate, the
Company shall (at the Registered Holder's expense) execute and deliver in lieu
of such certificate a new certificate of like kind representing the same rights
represented by such lost, stolen, destroyed or mutilated certificate and dated
the date of such lost, stolen, destroyed or mutilated certificate.

   Section 10. Notices. All notices referred to in this Warrant shall be in
               -------
writing and shall be delivered personally, sent by nationally recognized
overnight courier service (charges prepaid) or sent by registered or certified
mail, return receipt requested, postage prepaid and shall be deemed to have
been given (x) if delivered personally, on the date of delivery, (y) if
delivered by overnight courier service, on the date of delivery as evidenced by
the records of the courier service, and (z) if delivered by U.S. mail, 10 days
after having been deposited in the U.S. Mail (i) to the Company, at its
principal executive offices and (ii) to the Registered Holder of this Warrant,
at such holder's address as it appears in the records of the Company (unless
otherwise indicated by any such holder by notice given in accordance with this
Section).

                                     - 6 -

<PAGE>

   Section 11. Amendment and Waiver. Except as otherwise provided herein, the
               --------------------
provisions of this Warrant may be amended and the Company may take any action
herein prohibited, or omit to perform any act herein required to be performed
by it, only if the Company has obtained the written consent of the Registered
Holder of the Warrant.

   Section 12. Descriptive Headings; Governing Law. The descriptive headings of
               -----------------------------------
the several Sections and paragraphs of this Warrant are inserted for
convenience only and do not constitute a part of this Warrant. The laws of the
State of New York shall govern all issues concerning the relative rights of the
Company and the Registered Holders and the construction, validity, enforcement
and interpretation of this Warrant, without giving effect to any choice of law
or conflict of law provision or rule that would cause the application of the
laws of any jurisdictions other than the State of New York.

                                  * * * * * *

                                     - 7 -

<PAGE>

   IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by its
duly authorized officer and to be dated the Date of Issuance hereof.

                                          NEPHROS, INC.

                                          By /s/ Norman J. Barta
                                             ----------------------------------
                                          Its CEO
                                             ----------------------------------

                                     - 8 -

<PAGE>

                                                                      EXHIBIT I

                              EXERCISE AGREEMENT
                              ------------------

              To:                       Dated:

   The undersigned, pursuant to the provisions set forth in the attached
Warrant (Certificate No. W-    ), hereby agrees to subscribe for the purchase
of        shares of the Common Stock covered by such Warrant and makes payment
herewith by certified check in full therefor at the price per share provided by
such Warrant.

                                          Signature _____________

                                          Address ______________

                                     - 9 -

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