EXHIBIT 4.4.3

THE REGISTERED  HOLDER OF THIS UNIT PURCHASE  OPTION BY ITS  ACCEPTANCE  HEREOF,
AGREES  THAT IT WILL NOT SELL,  TRANSFER  OR ASSIGN  THIS UNIT  PURCHASE  OPTION
EXCEPT AS HEREIN PROVIDED AND THE REGISTERED HOLDER OF THIS UNIT PURCHASE OPTION
AGREES THAT IT WILL NOT SELL, TRANSFER,  ASSIGN, PLEDGE OR HYPOTHECATE THIS UNIT
PURCHASE  OPTION FOR A PERIOD OF ONE HUNDRED  EIGHTY  (180) DAYS  FOLLOWING  THE
EFFECTIVE  DATE (DEFINED  BELOW) TO ANYONE OTHER THAN (I)  NEWBRIDGE  SECURITIES
CORPORATION ("NEWBRIDGE") I-BANKERS SECURITIES INCORPORATED ("I-BANKERS"), OR AN
UNDERWRITER OR A SELECTED DEALER IN CONNECTION WITH THE OFFERING, OR (II) A BONA
FIDE OFFICER OR PARTNER OF NEWBRIDGE OR I-BANKERS OR OF ANY SUCH  UNDERWRITER OR
SELECTED DEALER.

THIS  UNIT  PURCHASE  OPTION  IS  NOT  EXERCISABLE  PRIOR  TO THE  LATER  OF THE
CONSUMMATION  BY SAND HILL IT SECURITY  ACQUISITION  CORP.  (THE "COMPANY") OF A
MERGER,  CAPITAL STOCK  EXCHANGE,  ASSET  ACQUISITION OR OTHER SIMILAR  BUSINESS
COMBINATION  (THE  "BUSINESS  COMBINATION")  (AS  DESCRIBED  MORE  FULLY  IN THE
COMPANY'S  REGISTRATION STATEMENT (DEFINED HEREIN)) OR JULY 25, 2005. VOID AFTER
5:00 P.M. EASTERN TIME, JULY 25 2009.

                                                                       No. UPO-4

                              UNIT PURCHASE OPTION

                               FOR THE PURCHASE OF

                                  22,200 UNITS

                                       OF

                     SAND HILL IT SECURITY ACQUISITION CORP.


     1. Unit Purchase Option.

     THIS CERTIFIES THAT, in  consideration of $100 duly paid by or on behalf of
Maxim  Group,  LLC, (a  "Holder"),  as  registered  owner of this Unit  Purchase
Option, to Sand Hill IT Security  Acquisition  Corp. (the "Company"),  Holder is
entitled, at any time or from time to time upon the later of the consummation of
a Business  Combination or July 25, 2005 (the  "Commencement  Date"),  and at or
before 5:00 p.m.,  Eastern Time, July 25, 2009 (the "Expiration  Date"), but not
thereafter,  to subscribe for, purchase and receive,  in whole or in part, up to
Twenty Two Thousand  Two Hundred  (22,200)  units (the  "Units") of the Company,
each Unit  consisting  of one share of common  stock of the  Company,  par value
$0.01 per share  (the  "Common  Stock"),  and two  warrants  (the  "Warrant(s)")
expiring  five  years  from the  effective  date (the  "Effective  Date") of the
registration  statement (the "Registration  Statement")  pursuant to which Units
are offered for sale to the public (the "Offering"). Each Warrant is the same as
the warrants  included in the Units being registered for sale to the public (the
"Public  Warrants")  under the  Securities  Act of 1933,  as amended (the "Act")
except that the exercise price of the Warrants shall be $6.65 per share.  If the
Expiration Date is a day on which banking  institutions are authorized by law to
close,  then this Unit Purchase  Option may be exercised on the next  succeeding
day which is not such a day in  accordance  with the terms  herein.  During  the
period ending on the Expiration  Date, the Company agrees not to take any action
that would  terminate the Unit  Purchase  Option.  This Unit Purchase  Option is
initially  exercisable at $7.50 per Unit so purchased;  provided,  however, that

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<PAGE>

upon the  occurrence  of any of the events  specified  in Section 6 hereof,  the
rights  granted by this Unit Purchase  Option,  including the exercise price per
Unit and the number of Units (and  shares of Common  Stock and  Warrants)  to be
received upon such exercise,  shall be adjusted as therein  specified.  The term
"Exercise Price" shall mean the initial exercise price or the adjusted  exercise
price, depending on the context.

     2. Exercise.

          (a)  Exercise  Procedure.  In order to  exercise  this  Unit  Purchase
Option,  the exercise form  attached  hereto must be duly executed and completed
and  delivered  to the  Company,  together  with this Unit  Purchase  Option and
payment of the Exercise Price for the Units being  purchased  payable in cash or
by  certified  check  or  official  bank  check.  If  the  subscription   rights
represented  hereby shall not be exercised at or before 5:00 p.m., Eastern time,
on the  Expiration  Date this Unit  Purchase  Option  shall  become  and be void
without further force or effect,  and all rights  represented hereby shall cease
and expire.

          (b) Legend.  Each certificate for the securities  purchased under this
Unit Purchase  Option shall bear a legend as follows unless such securities have
been registered under the Securities Act of 1933, as amended (the "Act"):

          "The  securities  represented by this  certificate  have not
          been registered under the Securities Act of 1933, as amended
          (the "Act") or applicable  state law. The securities may not
          be offered for sale,  sold or otherwise  transferred  except
          pursuant to an effective  registration  statement  under the
          Act, or pursuant to an exemption from registration under the
          Act and applicable state law."

          (c)  Cashless  Exercise.  (i) In lieu of the  payment of the  Exercise
Price  multiplied by the number of Units for which this Unit Purchase  Option is
exercisable (and in lieu of being entitled to receive Common Stock and Warrants)
in the manner  required by Section  2.(a),  the Holder shall have the right (but
not the obligation) to convert any  exercisable but unexercised  portion of this
Unit  Purchase  Option  into Units (the  "Conversion  Right") as  follows:  upon
exercise  of the  Conversion  Right,  the  Company  shall  deliver to the Holder
(without payment by the Holder of any of the Exercise Price in cash) that number
of shares of Common Stock and Warrants  comprising that number of Units equal to
the  quotient  obtained  by dividing  (x) the "Value" (as defined  below) of the
portion of the Unit Purchase  Option being  converted by (y) the Current  Market
Value (as defined below). The "Value" of the portion of the Unit Purchase Option
being converted shall equal the remainder  derived from  subtracting (a) (i) the
Exercise Price  multiplied by (ii) the number of Units underlying the portion of
this Unit Purchase Option being converted from (b) the Current Market Value of a
Unit  multiplied  by the  number of Units  underlying  the  portion  of the Unit
Purchase Option being converted. As used herein, the term "Current Market Value"
per Unit at any date  means  the  remainder  derived  from  subtracting  (x) the
exercise  price of the  Warrants  multiplied  by the  number of shares of Common
Stock  issuable upon exercise of the Warrants  underlying  one Unit from (y) the
Current  Market Price of the Common Stock  multiplied by the number of shares of
Common Stock underlying the Warrants and the Common Stock issuable upon exercise
of one Unit.  The "Current  Market  Price" of a share of Common Stock shall mean
(i) if the Common Stock is listed on a national securities exchange or quoted on
the Nasdaq  National  Market,  Nasdaq SmallCap Market or NASD OTC Bulletin Board
(or successor such as the Bulletin Board  Exchange),  the last sale price of the
Common Stock in the principal trading market for the Common Stock as reported by
the  exchange,  Nasdaq or the NASD, as the case may be; (ii) if the Common Stock
is not listed on a national securities exchange or quoted on the Nasdaq National
Market, Nasdaq SmallCap Market or the NASD OTC Bulletin Board (or successor such
as the Bulletin Board Exchange), but is traded in the residual  over-the-counter

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<PAGE>

market,  the  closing  bid price for the Common  Stock on the last  trading  day
preceding  the date in question  for which such  quotations  are reported by the
Pink Sheets, LLC or similar publisher of such quotations;  and (iii) if the fair
market value of the Common Stock cannot be determined  pursuant to clause (i) or
(ii) above, such price as the Board of Directors of the Company shall determine,
in good faith.

               (ii) The Cashless  Exercise  Right may be exercised by the Holder
on any  business  day on or after the  Commencement  Date and not later than the
Expiration  Date by delivering  the Unit Purchase  Option with the duly executed
exercise form attached hereto with the cashless  exercise  section  completed to
the Company,  exercising  the Cashless  Exercise  Right and specifying the total
number of Units the Holder  will  purchase  pursuant to such  Cashless  Exercise
Right.

     3.   Transfer.

          (a) Restrictions--General. The registered Holder of this Unit Purchase
Option,  by its  acceptance  hereof,  agrees  that it will not  sell,  transfer,
assign,  pledge or  hypothecate  this Unit  Purchase  Option for a period of one
hundred  eighty (180) days following the Effective Date to anyone other than (i)
Newbridge or I-Bankers or an underwriter or a selected dealer in connection with
the  Offering,  or (ii) a bona fide officer or partner of Newbridge or I-Bankers
or of  any  such  underwriter  or  selected  dealer.  On  and  after  the  first
anniversary  of the Effective  Date,  transfers to others may be made subject to
compliance with or exemptions from applicable  securities laws. In order to make
any permitted assignment,  the Holder must deliver to the Company the assignment
form  attached  hereto  duly  executed  and  completed,  together  with the Unit
Purchase Option and payment of all transfer taxes, if any, payable in connection
therewith.  The Company  shall  within five  business  days  transfer  this Unit
Purchase  Option on the books of the Company and shall execute and deliver a new
Unit Purchase  Option or Unit Purchase  Options of like tenor to the appropriate
assignee(s)  expressly  evidencing the right to purchase the aggregate number of
Units  purchasable  hereunder  or  such  portion  of such  number  as  shall  be
contemplated by any such assignment.

          (b)  Restrictions--Securities.  The securities  evidenced by this Unit
Purchase  Option shall not be  transferred  unless and until (i) the Company has
received  the  opinion of  counsel  for the Holder  that the  securities  may be
transferred  pursuant  to an  exemption  from  registration  under  the  Act and
applicable  state  securities  laws, the availability of which is established to
the reasonable satisfaction of the Company (the Company hereby agreeing that the
opinion of Jenkens &  Gilchrist  shall be deemed  satisfactory  evidence  of the
availability  of  an  exemption),   or  (ii)  a  registration   statement  or  a
post-effective   amendment  to  the  Registration  Statement  relating  to  such
securities  has  been  filed  by  the  Company  and  declared  effective  by the
Securities  and Exchange  Commission  (the  "Commission")  and  compliance  with
applicable state securities law has been established.

     4.   New Purchase Options to be Issued.

          (a) Partial Exercise. Subject to the restrictions in Section 3 hereof,
this Unit  Purchase  Option may be exercised or assigned in whole or in part. In
the event of the exercise or assignment  hereof in part only,  upon surrender of
this Unit  Purchase  Option for  cancellation,  together  with the duly executed
exercise or  assignment  form and funds  sufficient  to pay any  Exercise  Price
and/or  transfer  tax,  the Company  shall cause to be  delivered  to the Holder
without  charge a new Unit  Purchase  Option of like tenor to this Unit Purchase
Option in the name of the Holder  evidencing the right of the Holder to purchase
the number of Units purchasable  hereunder as to which this Unit Purchase Option
has not been exercised or assigned.

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<PAGE>

          (b) Loss, Theft, Destruction.  Upon receipt by the Company of evidence
satisfactory  to it of the loss,  theft,  destruction or mutilation of this Unit
Purchase Option and of reasonably satisfactory indemnification or the posting of
a bond, the Company shall execute and deliver a new Unit Purchase Option of like
tenor and date.  Any such new Unit Purchase  Option  executed and delivered as a
result of such  loss,  theft,  mutilation  or  destruction  shall  constitute  a
substitute contractual obligation on the part of the Company.

     5.   Registration Rights.

          (a) Demand Registration.

               (i)  The  Company,  upon  written  demand  (the  "Initial  Demand
Notice") of the  Holder(s) of at least 51% of the Unit Purchase  Options  and/or
the underlying Units and/or the underlying  securities (the "Majority Holders"),
agrees to register  on one  occasion,  all or any  portion of the Unit  Purchase
Options  requested by the Majority  Holders in the Initial Demand Notice and all
of the securities  underlying such Unit Purchase  Options,  including the Units,
Common  Stock,  the  Warrants  and the  Common  Stock  underlying  the  Warrants
(collectively, the "Registrable Securities"). On such occasion, the Company will
file a registration statement or a post-effective  amendment to the Registration
Statement covering the Registrable Securities within sixty days after receipt of
the Initial  Demand  Notice and use its best  efforts to have such  registration
statement or  post-effective  amendment  declared  effective as soon as possible
thereafter.  The demand for registration may be made at any time during a period
of five years beginning on the Effective Date. The Company  covenants and agrees
to give  written  notice of its  receipt  of any  Initial  Demand  Notice by any
Holder(s) to all other  registered  Holders of the Unit Purchase  Options and/or
the Registrable  Securities  within ten days from the date of the receipt of any
such Initial Demand Notice.

               (ii) The Company  shall bear all fees and  expenses  attendant to
registering  the  Registrable  Securities,  including  the expenses of any legal
counsel selected by the Holders to represent them in connection with the sale of
the Registrable  Securities,  but the Holders shall pay any and all underwriting
commissions. The Company agrees to use its reasonable best efforts to qualify or
register the Registrable  Securities in such states as are reasonably  requested
by the Majority Holder(s); provided, however, that in no event shall the Company
be required  to register  the  Registrable  Securities  in a state in which such
registration  would  cause (i) the  Company  to be  obligated  to  qualify to do
business  in such state,  or would  subject the Company to taxation as a foreign
corporation   doing  business  in  such   jurisdiction  or  (ii)  the  principal
stockholders  of the Company to be  obligated  to escrow their shares of capital
stock of the  Company.  The Company  shall cause any  registration  statement or
post-effective  amendment  filed  pursuant to the demand  rights  granted  under
Section 5.1.1 to remain effective for a period of nine  consecutive  months from
the effective date of such registration statement or post-effective amendment.

          (b)  "Piggy-Back" Registration.

               (i) In addition to the demand right of registration,  the Holders
of the Unit  Purchase  Options  shall have the right for a period of seven years
commencing on the Effective Date, to include the Registrable  Securities as part
of any other  registration  of  securities  filed by the Company  (other than in
connection with a transaction  contemplated by Rule 145(a) promulgated under the
Act or pursuant to Form S-8); provided, however, that if, in the written opinion
of the  Company's  managing  underwriter  or  underwriters,  if  any,  for  such

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<PAGE>

offering,  the  inclusion  of the  Registrable  Securities,  when  added  to the
securities being registered by the Company or the selling  stockholder(s),  will
exceed the maximum amount of the Company's  securities which can be marketed (i)
at a price  reasonably  related to their then  current  market  value,  and (ii)
without materially and adversely affecting the entire offering, then the Company
will still be required to include the  Registrable  Securities,  but may require
the Holders to agree, in writing, to delay the sale of all or any portion of the
Registrable  Securities  for a period of 90 days from the effective  date of the
offering,  provided,  further, that if the sale of any Registrable Securities is
so delayed, then the number of securities to be sold by all stockholders in such
public  offering  during such 90 day period shall be apportioned  pro rata among
all  such  selling  stockholders,  including  all  holders  of  the  Registrable
Securities,  according to the total amount of securities of the Company owned by
said selling stockholders, including all holders of the Registrable Securities.

               (ii) The Company  shall bear all fees and  expenses  attendant to
registering  the  Registrable  Securities,  including  the expenses of any legal
counsel selected by the Holders to represent them in connection with the sale of
the  Registrable  Securities but the Holders shall pay any and all  underwriting
commissions  related  to the  Registrable  Securities.  In the  event  of such a
proposed registration, the Company shall furnish the then Holders of outstanding
Registrable  Securities  with not less than fifteen days written notice prior to
the proposed date of filing of such registration  statement.  Such notice to the
Holders shall continue to be given for each  applicable  registration  statement
filed (during the period in which the Unit Purchase  Option is  exercisable)  by
the  Company  until  such time as all of the  Registrable  Securities  have been
registered and sold. The holders of the  Registrable  Securities  shall exercise
the "piggy-back" rights provided for herein by giving written notice, within ten
days  of the  receipt  of  the  Company's  notice  of its  intention  to  file a
registration statement. The Company shall cause any registration statement filed
pursuant to the above  "piggyback"  rights to remain effective for at least nine
months from the date that the Holders of the  Registrable  Securities  are first
given the opportunity to sell all of such securities.

          (c) Damages. Should the registration or the effectiveness thereof
required  by  Sections  5(a) and 5(b)  hereof be delayed  by the  Company or the
Company  otherwise fails to comply with such  provisions,  the Company shall, in
addition to any other equitable or other relief  available to the Holder(s),  be
liable for any and all incidental,  special and consequential  damages sustained
by the  Holder(s),  including,  but not limited to, the loss of any profits that
might have been  received by the Holder upon the sale of shares of Common  Stock
or Warrants (and shares of Common Stock underlying the Warrants) underlying this
Unit Purchase Option.

          (d)   Indemnification.

               (i) The Company shall  indemnify the Holder(s) of the Registrable
Securities to be sold pursuant to any registration  statement hereunder and each
person,  if any, who controls  such Holders  within the meaning of Section 15 of
the Act or Section 20(a) of the Securities Exchange Act of 1934, as amended (the
"Exchange  Act"),  against  all  loss,  claim,  damage,   expense  or  liability
(including all reasonable attorneys' fees and other expenses reasonably incurred
in  investigating,  preparing  or  defending  against  litigation,  commenced or
threatened,  or any claim  whatsoever  whether arising out of any action between
the  Underwriter  and the Company or between the Underwriter and any third party
or  otherwise)  to which  any of them may  become  subject  under  the Act,  the
Exchange Act or otherwise,  arising from such registration statement but only to
the same extent and with the same effect as the provisions pursuant to which the
Company has agreed to indemnify the  Underwriters  contained in Section 5 of the
Underwriting  Agreement  between the Company,  Newbridge  and  I-Bankers and the
other  Underwriters named therein dated the Effective Date. The Holder(s) of the
Registrable Securities to be sold pursuant to such registration  statement,  and
their successors and assigns,  shall severally,  and not jointly,  indemnify the
Company,  its officers and directors  and each person,  if any, who controls the
Company  within the  meaning  of  Section 15 of the Act or Section  20(a) of the
Exchange Act, against all loss, claim,  damage,  expense or liability (including
all  reasonable  attorneys'  fees and  other  expenses  reasonably  incurred  in

                                       5
<PAGE>

investigating,  preparing or defending  against any claim  whatsoever)  to which
they may become  subject under the Act, the Exchange Act or  otherwise,  arising
from information  furnished by or on behalf of such Holders, or their successors
or assigns, in writing, for specific inclusion in such registration statement to
the same extent and with the same effect as the provisions  contained in Section
5 of the Underwriting  Agreement  pursuant to which the Underwriters have agreed
to indemnify the Company.

               (ii)  Nothing  contained  in this Unit  Purchase  Option shall be
construed as requiring the Holder(s) to exercise their Unit Purchase  Options or
Warrants  underlying  such Unit  Purchase  Options prior to or after the initial
filing of any registration statement or the effectiveness thereof.

               (iii) The Company  shall  furnish  Newbridge  and  I-Bankers,  as
representatives of the Holders  participating in any of the foregoing offerings,
a signed counterpart,  addressed to the participating Holders, of (i) an opinion
of  counsel  to the  Company,  dated  the  effective  date of such  registration
statement (and, if such registration  includes an underwritten  public offering,
an  opinion  dated  the date of the  closing  under any  underwriting  agreement
related  thereto),  and (ii) a "cold comfort" letter dated the effective date of
such registration  statement (and, if such registration includes an underwritten
public  offering,  a letter dated the date of the closing under the underwriting
agreement) signed by the independent public accountants who have issued a report
on the Company's financial  statements included in such registration  statement,
in each case  covering  substantially  the same  matters  with  respect  to such
registration statement (and the prospectus included therein) and, in the case of
such accountants'  letter, with respect to events subsequent to the date of such
financial statements, as are customarily covered in opinions of issuer's counsel
and in accountants'  letters  delivered to  underwriters in underwritten  public
offerings of  securities.  The Company shall also deliver  promptly to Newbridge
and I-Bankers,  as representatives of the Holders participating in the offering,
the   correspondence   and   memoranda   described   below  and  copies  of  all
correspondence  between the Commission and the Company,  its counsel or auditors
and all memoranda  relating to discussions with the Commission or its staff with
respect to the  registration  statement and permit  Newbridge and I-Bankers,  as
representatives  of the  Holders,  to do  such  investigation,  upon  reasonable
advance  notice,  with respect to  information  contained in or omitted from the
registration   statement  as  it  deems  reasonably  necessary  to  comply  with
applicable  securities  laws or rules of the National  Association of Securities
Dealers,  Inc. (the "NASD").  Such investigation  shall include access to books,
records and properties and  opportunities to discuss the business of the Company
with its officers and independent auditors, all to such reasonable extent and at
such   reasonable   times  and  as  often  as  Newbridge   and   I-Bankers,   as
representatives of the Holders,  shall reasonably request. The Company shall not
be  required  to  disclose  any  confidential  information  or other  records to
Newbridge and  I-Bankers,  as  representatives  of the Holders,  or to any other
person,  until and unless  such  persons  shall  have  entered  into  reasonable
confidentiality agreements (in form and substance reasonably satisfactory to the
Company), with the Company with respect thereto.

               (iv) The Company shall enter into an underwriting  agreement with
the managing  underwriter(s),  if any, selected by any Holders whose Registrable
Securities  are being  registered  pursuant  to this  Section 5, which  managing
underwriter shall be reasonably  acceptable to the Company. Such agreement shall
be reasonably satisfactory in form and substance to the Company, each Holder and
such managing underwriters,  and shall contain such representations,  warranties
and covenants by the Company and such other terms as are  customarily  contained
in agreements of that type used by the managing  underwriter.  The Holders shall
be parties to any  underwriting  agreement  relating to an underwritten  sale of

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<PAGE>

their Registrable  Securities and may, at their option,  require that any or all
the  representations,  warranties  and  covenants  of the  Company to or for the
benefit of such  underwriters  shall also be made to and for the benefit of such
Holders.  Such  Holders  shall not be  required to make any  representations  or
warranties to or agreements with the Company or the underwriters  except as they
may relate to such  Holders and their  intended  methods of  distribution.  Such
Holders,  however,  shall  agree  to  such  covenants  and  indemnification  and
contribution  obligations for selling stockholders as are customarily  contained
in  agreements  of that type used by the  managing  underwriter.  Further,  such
Holders shall execute  appropriate  custody  agreements and otherwise  cooperate
fully in the  preparation  of the  registration  statement  and other  documents
relating  to any  offering  in which they  include  securities  pursuant to this
Section 5. Each  Holder  shall  also  furnish to the  Company  such  information
regarding itself, the Registrable Securities held by it, and the intended method
of disposition of such securities as shall be reasonably  required to effect the
registration of the Registrable Securities.

               (v)  Notwithstanding  anything contained in this Section 5 to the
contrary, the Company shall have no obligation pursuant to Sections 5(a) or 5(b)
for the registration of Registrable Securities held by any Holder (i) where such
Holder  would then be  entitled  to sell  under Rule 144 within any  three-month
period (or such other  period  prescribed  under Rule 144 as may be  provided by
amendment  thereof) all of the Registrable  Securities then held by such Holder,
and (ii)  where the  number of  Registrable  Securities  held by such  Holder is
within the volume  limitations under paragraph (e) of Rule 144 (calculated as if
such Holder were an affiliate within the meaning of Rule 144).

               (vi) Each Holder agrees, that upon receipt of any notice from the
Company  of the  happening  of any  event as a result  of which  the  prospectus
included in the Registration  Statement,  as then in effect,  includes an untrue
statement of a material  fact or omits to state a material  fact  required to be
stated  therein or necessary to make the  statements  therein not  misleading in
light  of  the  circumstances  then  existing,   such  Holder  will  immediately
discontinue  disposition of Registrable  Securities pursuant to the Registration
Statement  covering such  Registrable  Securities until such Holder's receipt of
the copies of a supplemental  or amended  prospectus,  and, if so desired by the
Company,  such  Holder  shall  deliver  to the  Company  (at the  expense of the
Company)  or  destroy  (and  deliver  to  the  Company  a  certificate  of  such
destruction) all copies,  other than permanent file copies then in such Holder's
possession,  of the prospectus  covering such Registrable  Securities current at
the time of receipt of such notice.

     6.   Adjustments.

          (a) Exercise  Price and Number of  Securities.  The Exercise Price and
the number of Units  underlying  the Unit  Purchase  Option  shall be subject to
adjustment from time to time as hereinafter set forth:

               (i) If after the date hereof,  and subject to the  provisions  of
Section 6.3 below, the number of outstanding shares of Common Stock is increased
by a stock dividend payable in shares of Common Stock or by a split-up of shares
of Common Stock or other similar event, then, on the effective date thereof, the
number  of  shares  of Common  Stock  underlying  each of the Units  purchasable
hereunder  shall be  increased in  proportion  to such  increase in  outstanding
shares.  In such case,  the number of shares of Common  Stock,  and the exercise
price applicable  thereto,  underlying the Warrants underlying each of the Units
purchasable  hereunder  shall be  adjusted in  accordance  with the terms of the
Warrants.  For example, if the Company declares a two-for-one stock dividend and
at the time of such dividend  this Unit  Purchase  Option is for the purchase of
one  Unit at  $7.50  per  whole  Unit  (each  Warrant  underlying  the  Units is
exercisable for $2.50 per share), upon effectiveness of the dividend,  this Unit
Purchase  Option will be adjusted to allow for the purchase of one Unit at $7.50
per Unit,  each Unit  entitling the holder to receive two shares of Common Stock
and four Warrants (each Warrant exercisable for $2.50 per share).

                                       7
<PAGE>

               (ii) If after the date hereof,  and subject to the  provisions of
Section 6.4, the number of outstanding  shares of Common Stock is decreased by a
consolidation,  combination  or  reclassification  of shares of Common  Stock or
other similar event,  then, on the effective date thereof,  the number of shares
of Common Stock  underlying  each of the Units  purchasable  hereunder  shall be
decreased in proportion to such decrease in  outstanding  shares.  In such case,
the number of shares of Common Stock, and the exercise price applicable thereto,
issuable upon exercise of the Warrants included in each of the Units purchasable
hereunder shall be adjusted in accordance with the terms of the Warrants.

               (iii) In case of any  reclassification  or  reorganization of the
outstanding  shares of Common  Stock  other  than a change  covered  by  Section
6(a)(i) or 6(a)(ii)  hereof or that solely  affects the par value of such shares
of Common Stock,  or in the case of any merger or  consolidation  of the Company
with or into another  corporation (other than a consolidation or merger in which
the  Company  is the  continuing  corporation  and that  does not  result in any
reclassification  or reorganization of the outstanding  shares of Common Stock),
or in the case of any sale or conveyance to another corporation or entity of the
property  of the  Company as an  entirety  or  substantially  as an  entirety in
connection with which the Company is dissolved, the Holder of this Unit Purchase
Option shall have the right  thereafter  (until the  expiration  of the right of
exercise of this Unit Purchase Option) to receive upon the exercise hereof,  for
the same aggregate  Exercise Price payable  hereunder  immediately prior to such
event,  the kind and amount of shares of 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, by
a Holder of the number of shares of Common Stock of the Company  obtainable upon
exercise of this Unit Purchase  Option and the underlying  Warrants  immediately
prior to such event;  and if any  reclassification  also  results in a change in
shares of Common  Stock  covered  by  Section  6(a)(i)  or  6(a)(ii),  then such
adjustment shall be made pursuant to Sections 6(a)(i), 6(a)(ii) and this Section
6(a)(iii).  The provisions of this Section  6(a)(iii)  shall  similarly apply to
successive reclassifications,  reorganizations, mergers or consolidations, sales
or other transfers.

               (iv)  This  form of Unit  Purchase  Option  need  not be  changed
because of any change pursuant to this Section, and Unit Purchase Options issued
after such change may state the same Exercise Price and the same number of Units
as are stated in the Unit Purchase  Options  initially  issued  pursuant to this
Agreement.  The  acceptance  by any Holder of the issuance of new Unit  Purchase
Options  reflecting a required or permissive change shall not be deemed to waive
any  rights  to an  adjustment  occurring  after  the  Commencement  Date or the
computation thereof.

          (b) Substitute Unit Purchase Option.  In case of any  consolidation of
the Company  with, or merger of the Company with, or merger of the Company into,
another  corporation (other than a consolidation or merger which does not result
in  any  reclassification  or  change  of the  outstanding  Common  Stock),  the
corporation  formed by such consolidation or merger shall execute and deliver to
the Holder a supplemental Unit Purchase Option providing that the holder of each
Unit Purchase Option then outstanding or to be outstanding  shall have the right
thereafter  (until  the  stated  expiration  of such Unit  Purchase  Option)  to
receive,  upon  exercise of such Unit  Purchase  Option,  the kind and amount of
shares  of  stock  and  other  securities  and  property  receivable  upon  such
consolidation or merger,  by a holder of the number of shares of Common Stock of
the  Company  for which such Unit  Purchase  Option  might  have been  exercised
immediately  prior  to  such  consolidation,  merger,  sale  or  transfer.  Such
supplemental  Unit Purchase Option shall provide for adjustments  which shall be
identical to the adjustments  provided in Section 6. The above provision of this
Section shall similarly apply to successive consolidations or mergers.

                                       8
<PAGE>

          (c) Fractional  Interests.  The Company shall not be required to issue
certificates  representing  fractions of shares of Common Stock or Warrants upon
the  exercise  of the Unit  Purchase  Option,  nor shall it be required to issue
scrip or pay cash in lieu of any  fractional  interests,  it being the intent of
the parties that all  fractional  interests  shall be eliminated by rounding any
fraction up to the nearest  whole number of Warrants,  shares of Common Stock or
other securities, properties or rights.

     7. Reservation and Listing. The Company shall at all times reserve and keep
available out of its authorized  shares of Common Stock,  solely for the purpose
of  issuance  upon  exercise  of the  Unit  Purchase  Options  or  the  Warrants
underlying  the Unit Purchase  Option,  such number of shares of Common Stock or
other  securities,  properties  or rights as shall be issuable upon the exercise
thereof.  The  Company  covenants  and agrees  that,  upon  exercise of the Unit
Purchase  Options  and payment of the  Exercise  Price  therefor,  all shares of
Common Stock and other securities  issuable upon such exercise shall be duly and
validly  issued,  fully paid and  non-assessable  and not subject to  preemptive
rights of any  stockholder.  The Company further  covenants and agrees that upon
exercise of the Warrants underlying the Unit Purchase Options and payment of the
respective Warrant exercise price therefor, all shares of Common Stock and other
securities  issuable upon such exercise shall be duly and validly issued,  fully
paid and non-assessable and not subject to preemptive rights of any stockholder.
As long as the Unit Purchase Options shall be outstanding, the Company shall use
its best efforts to cause all (i) Units and shares of Common Stock issuable upon
exercise of the Unit Purchase Options,  (iii) Warrants issuable upon exercise of
the Unit Purchase Options and (iv) shares of Common Stock issuable upon exercise
of the  Warrants  included  in the  Units  issuable  upon  exercise  of the Unit
Purchase  Option to be listed  (subject to official  notice of  issuance) on all
securities exchanges (or, if applicable on the Nasdaq National Market,  SmallCap
Market,  OTC Bulletin Board or any successor trading market) on which the Units,
the Common  Stock or the  Public  Warrants  issued to the  public in  connection
herewith may then be listed and/or quoted.

     8.   Certain Notice Requirements.

          (a) Right to Notice.  Nothing  herein shall be construed as conferring
upon the Holders the right to vote or consent as a stockholder  for the election
of  directors  or any other  matter,  or as having  any rights  whatsoever  as a
stockholder of the Company.  If, however, at any time prior to the expiration of
the Unit Purchase  Options and their  exercise,  any of the events  described in
Section 8(b) shall occur, then, in one or more of said events, the Company shall
give written  notice of such event at least fifteen days prior to the date fixed
as a record date or the date of closing the transfer books for the determination
of the  stockholders  entitled to such  dividend,  distribution,  conversion  or
exchange  of  securities  or  subscription  rights,  or entitled to vote on such
proposed dissolution, liquidation, winding up or sale. Such notice shall specify
such record date or the date of the closing of the transfer  books,  as the case
may be. Notwithstanding the foregoing,  the Company shall deliver to each Holder
a copy of each notice given to the other stockholders of the Company at the same
time and in the same manner that such notice is given to the stockholders.

          (b)  Enumerated  Events.  The  Company  shall be  required to give the
notice described in this Section 8 upon one or more of the following events: (i)
if the Company  shall take a record of the holders of its shares of Common Stock
for the purpose of entitling them to receive a dividend or distribution  payable
otherwise  than in cash, or a cash dividend or  distribution  payable  otherwise
than out of retained earnings,  as indicated by the accounting treatment of such
dividend or distribution on the books of the Company,  or (ii) the Company shall
offer to all the holders of its Common  Stock any  additional  shares of capital
stock of the Company or securities  convertible  into or exchangeable for shares
of capital  stock of the Company,  or any option,  right or warrant to subscribe
therefor,  or (iii) a  dissolution,  liquidation  or winding  up of the  Company

                                       9
<PAGE>

(other than in connection  with a  consolidation  or merger) or a sale of all or
substantially all of its property, assets and business shall be proposed.

          (c) Change in Exercise  Price.  The Company  shall,  promptly after an
event  requiring a change in the  Exercise  Price  pursuant to Section 6 hereof,
send notice to the Holders of such event and change  (the "Price  Notice").  The
Price  Notice  shall  describe  the event  causing  the change and the method of
calculating  same and  shall be  certified  as being  true and  accurate  by the
Company's President and Chief Financial Officer.

          (d)  Notice  Delivery.  All  notices,  requests,  consents  and  other
communications  under this Unit Purchase Option shall be in writing and shall be
deemed to have been duly made when hand delivered,  or mailed by express mail or
private courier  service:  (i) If to the registered  Holder of the Unit Purchase
Option,  to the address of such Holder as shown on the books of the Company,  or
(ii) If to the Company, to the following address or to such other address as the
Company may designate by notice to the Holders:

                          Sand Hill IT Security Acquisition Corp.
                          3000 Sand Hill Road
                          Building 1, Suite 240
                          Menlo Park, CA  94025
                          Attn:  President


     9.   Miscellaneous.

          (a)  Amendments.  The  Company  and  Newbridge  may from  time to time
supplement or amend this Unit Purchase Option without the approval of any of the
Holders in order to cure any  ambiguity,  to correct or supplement any provision
contained herein that may be defective or inconsistent with any other provisions
herein,  or to make any  other  provisions  in regard to  matters  or  questions
arising hereunder that the Company and Newbridge may deem necessary or desirable
and that the Company and Newbridge deem shall not adversely  affect the interest
of the Holders.  All other modifications or amendments shall require the written
consent  of  and  be  signed  by  the  party  against  whom  enforcement  of the
modification or amendment is sought.

          (b) Headings.  The headings  contained herein are for the sole purpose
of  convenience  of  reference,  and shall  not in any way  limit or affect  the
meaning  or  interpretation  of any of the  terms  or  provisions  of this  Unit
Purchase Option.

     10. Entire  Agreement.  This Unit Purchase Option  (together with the other
agreements and documents being delivered  pursuant to or in connection with this
Unit Purchase  Option)  constitutes  the entire  agreement of the parties hereto
with respect to the subject matter hereof,  and supersedes all prior  agreements
and understandings of the parties, oral and written, with respect to the subject
matter hereof.

          (a) Binding  Effect.  This Unit Purchase  Option shall inure solely to
the benefit of, and shall be binding upon,  the Holder and the Company and their
permitted assignees,  respective  successors,  legal representative and assigns,
and no other  person  shall have or be  construed to have any legal or equitable
right, remedy or claim under or in respect of or by virtue of this Unit Purchase
Option or any provisions herein contained.


                                       10
<PAGE>

          (b) Governing Law. This Unit Purchase  Option shall be governed by and
construed  and  enforced in  accordance  with the laws of the State of New York,
without  giving effect to conflict of laws.  The Company  hereby agrees that any
action, proceeding or claim against it arising out of, or relating in any way to
this Unit  Purchase  Option  shall be brought and  enforced in the courts of the
State of New York or of the United  States of America for the Southern  District
of New York, and irrevocably  submits to such  jurisdiction,  which jurisdiction
shall be exclusive.  The Company  hereby waives any objection to such  exclusive
jurisdiction and that such courts  represent an inconvenient  forum. Any process
or summons to be served upon the Company  may be served by  transmitting  a copy
thereof by registered  or certified  mail,  return  receipt  requested,  postage
prepaid,  addressed  to it at the  address  set forth in Section 8 hereof.  Such
mailing shall be deemed personal service and shall be legal and binding upon the
Company in any action,  proceeding  or claim.  The Company and the Holder  agree
that the  prevailing  party(ies) in any such action shall be entitled to recover
from the other  party(ies)  all of its reasonable  attorneys'  fees and expenses
relating to such action or proceeding  and/or  incurred in  connection  with the
preparation therefor.

          (c)  Waivers.  The failure of the Company or the Holder to at any time
enforce any of the  provisions of this Unit Purchase  Option shall not be deemed
or construed to be a waiver of any such provision,  nor to in any way affect the
validity of this Unit Purchase  Option or any  provision  hereof or the right of
the Company or any Holder to thereafter enforce each and every provision of this
Unit Purchase Option. No waiver of any breach, non-compliance or non-fulfillment
of any of the provisions of this Unit Purchase Option shall be effective  unless
set forth in a written instrument  executed by the party or parties against whom
or which enforcement of such waiver is sought; and no waiver of any such breach,
non-compliance or non-fulfillment shall be construed or deemed to be a waiver of
any other or subsequent breach, non-compliance or non-fulfillment.

          (d) Counterparts.  This Unit Purchase Option may be executed in one or
more counterparts, and by the different parties hereto in separate counterparts,
each of which shall be deemed to be an original, but all of which taken together
shall constitute one and the same agreement, and shall become effective when one
or more counterparts has been signed by each of the parties hereto and delivered
to each of the other parties hereto.

          (e) Exchange  Agreement.  As a condition  of the Holder's  receipt and
acceptance of this Unit Purchase  Option,  Holder agrees that, at any time prior
to the complete  exercise of this Unit Purchase Option by Holder, if the Company
and Newbridge  enter into an agreement  (the "Exchange  Agreement")  pursuant to
which they agree that all  outstanding  Unit Purchase  Options will be exchanged
for securities or cash or a combination of both, then Holder shall agree to such
exchange and become a party to the Exchange Agreement.

     IN WITNESS WHEREOF,  the Company has caused this Unit Purchase Option to be
signed by its duly authorized officer as of the 30th day of July, 2004.


                                   SAND HILL IT SECURITY ACQUISITION CORP.


                                   By: /s/ Cary Grossman
                                   -------------------------------------------
                                   Name:  Cary Grossman
                                   Title: Vice President and Chief Financial
                                          Officer

                                       11
<PAGE>

FORM TO BE USED TO EXERCISE UNIT PURCHASE OPTION
------------------------------------------------



Sand Hill IT Security Acquisition Corp.
3000 Sand Hill Road
Building 1, Suite 240
Menlo Park, CA  94025

Date: _________________, 2004

     The undersigned  hereby elects  irrevocably to exercise all or a portion of
the  within  Unit  Purchase  Option and to  purchase  ____ Units of Sand Hill IT
Security  Acquisition  Corp. and hereby makes payment of  $____________  (at the
rate of $_________ per Unit) in payment of the Exercise Price pursuant  thereto.
Please issue the Common Stock and Warrants as to which this Unit Purchase Option
is exercised in accordance with the instructions given below. or

     The undersigned  hereby elects irrevocably to convert its right to purchase
_________ Units  purchasable  under the within Unit Purchase Option by surrender
of the unexercised  portion of the attached Unit Purchase Option (with a "Value"
based of  $________  based on a "Market  Price" of  $_______).  Please issue the
securities  comprising  the  Units as to which  this  Unit  Purchase  Option  is
exercised in accordance with the instructions given below.


                                             -----------------------------
                                             Signature

                                             -----------------------------
                                             Signature Guaranteed


                   INSTRUCTIONS FOR REGISTRATION OF SECURITIES

Name ________________________________________________________________________
                            (Print in Block Letters)

Address ______________________________________________________________________

     NOTICE: THE SIGNATURE TO THIS FORM MUST CORRESPOND WITH THE NAME AS WRITTEN
     UPON  THE FACE OF THE  WITHIN  UNIT  PURCHASE  OPTION  IN EVERY  PARTICULAR
     WITHOUT  ALTERATION OR  ENLARGEMENT OR ANY CHANGE  WHATSOEVER,  AND MUST BE
     GUARANTEED  BY A BANK,  OTHER THAN A SAVINGS BANK, OR BY A TRUST COMPANY OR
     BY A FIRM HAVING MEMBERSHIP ON A REGISTERED NATIONAL SECURITIES EXCHANGE.


                                       12
<PAGE>

FORM TO BE USED TO ASSIGN UNIT PURCHASE OPTION
----------------------------------------------



                                   ASSIGNMENT

(To be executed by the registered Holder to effect a transfer of the within Unit
Purchase Option)

     FOR VALUE RECEIVED, ___________________________________________ does hereby
sell, assign and transfer  unto_______________________________________ the right
to purchase  __________  Units of Sand Hill IT Security  Acquisition  Corp. (the
"Company")  evidenced  by the  within  Unit  Purchase  Option  and  does  hereby
authorize the Company to transfer such right on the books of the Company.

Dated:   ________________, 2004


                                          -----------------------------
                                          Signature


                                          -----------------------------
                                          Signature Guaranteed



NOTICE: THE SIGNATURE TO THIS FORM MUST CORRESPOND WITH THE NAME AS WRITTEN UPON
THE  FACE OF THE  WITHIN  UNIT  PURCHASE  OPTION  IN  EVERY  PARTICULAR  WITHOUT
ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATSOEVER,  AND MUST BE GUARANTEED BY A
BANK,  OTHER THAN A SAVINGS  BANK,  OR BY A TRUST  COMPANY  OR BY A FIRM  HAVING
MEMBERSHIP ON A REGISTERED NATIONAL SECURITIES EXCHANGE.



                                       13