FIRST AMENDMENT TO
   SECOND AMENDED AND RESTATED TERM LOAN AND ACQUISITION CREDIT
                            AGREEMENT

     This FIRST AMENDMENT TO SECOND AMENDED AND RESTATED TERM
 LOAN AND ACQUISITION CREDIT AGREEMENT (the "First Amendment")
 is made as of the 22nd day of August, 1997 by and among
 ALARMGUARD, INC., a Delaware corporation, with its chief
 executive office located at 125 Frontage Road, Orange,
 Connecticut 06477 ("Borrower"), the Guarantors which are or may
 become parties to this First Amendment, the banks, financial
 institutions and other lenders which are or may become parties
 to this First Amendment (individually, a "Lender" and
 collectively, the "Lenders"), BANK OF BOSTON CONNECTICUT, a
 Connecticut savings bank, with its head office located at 100
 Pearl Street, Hartford, Connecticut 06103 as Administrative
 Agent for the Lenders (in such capacity, the "Administrative
 Agent"), and GENERAL ELECTRIC CAPITAL CORPORATION, a New York
 corporation, with an office located at 201 High Ridge Road,
 Stamford, Connecticut 06927-5100 as the Documentation Agent for
 the Lenders (in such capacity, the "Documentation Agent").

                      W I T N E S S E T H:

     Borrower, the Lenders, the Administrative Agent and the
 Documentation Agent entered into a certain Second Amended and
 Restated Term Loan and Acquisition Credit Agreement as of the
 15th day of April, 1997 (as amended and in effect from time to
 time, the "Credit Agreement") whereby the Lenders agreed to
 make loans and advances and otherwise extend credit to the
 Borrower.

     Borrower, the Lenders, the Administrative Agent and the
 Documentation Agent have agreed to amend the Credit Agreement
 in certain respects.

     Section 14.11. of the Credit Agreement provides that no
 modification or amendment of the Credit Agreement shall be
 effective unless the same shall be in writing and signed by the
 parties thereto.

     NOW, THEREFORE, in consideration of one dollar ($1.00) and
 other good and valuable consideration, the receipt and
 sufficiency of which are hereby acknowledged, Borrower, the
 Lenders, the Administrative Agent and the Documentation Agent
 hereby agree as follows:
 
1         Defined Terms.  Defined terms not defined herein shall
 have the meanings ascribed to them in the Credit Agreement.


2.   Amendment to Credit Agreement.

     (a)  Section 1.26. of the Credit Agreement, entitled
"Borrowing Base," is hereby amended and restated in its entirety
as follows:

     Section 1.26. "Borrowing Base" means, (a) as of any date as
     of which the amount thereof shall be determined during the
     period commencing as of August 22, 1997 and continuing
     through the earlier of (i) the Dividend Payment Date (as
     hereinafter defined) or (ii) December 31, 1997, an amount
     which is equal to RMR as of such date multiplied by 23.5
     and, (b) as of any other date as of which the amount
     thereof shall be determined, an amount which is equal to
     RMR as of such date multiplied by 22.5.  For purposes of
     this Section 1.26., the term "Dividend Payment Date" shall
     mean the date on which Alarmguard Holdings receives the
     proceeds of a certain dividend declared by Mission West
     Properties and scheduled to be paid in October, 1997.

     (b)  Section 3.2.4. of the Credit Agreement is hereby
amended and restated in its entirety as follows:

     Section 3.2.4. A pledge of all of Alarmguard Holding's
     right, title and interest in and to all shares of Capital
     Stock of SSH and Mission West Properties pursuant to the
     Alarmguard Holdings Pledge Agreement; provided, however,
     that as long as no Default or Event of Default shall have
     occurred or be continuing, the pledge of the shares of
     Capital Stock of Mission West Properties shall be released
     by the Administrative Agent as of the earlier of the
     Dividend Payment Date (as defined in Section 1.26.) or
     December 31, 1997.

3.   Confirmation of Agreements.  Borrower, the Lenders, the
Administrative Agent and the Documentation Agent hereby agree
that, except as provided in this First Amendment, the Credit
Agreement, the Notes and the Other Documents, and the grant of
the liens, security interests and other encumbrances thereunder,
and its agreements, covenants, obligations, representations and
warranties thereunder and therein are hereby expressly ratified,
confirmed and restated as of the date hereof.

4.   Effect of Amendment.  Borrower, the Lenders, the
Administrative Agent and the Documentation Agent hereby agree
and acknowledge that except as provided in this First Amendment,
the Credit Agreement remains in full force and effect and has
not been modified or amended in any respect, it being the
intention of Borrower, the Lenders, the Administrative Agent and
the Documentation Agent that this First Amendment and the Credit
Agreement be read, construed and interpreted as one and the same
instrument.

     IN WITNESS WHEREOF, Borrower, the Lenders, the
Administrative Agent and the Documentation Agent have executed
this First Amendment as of the date first above written.

                              THE BORROWER:
                              ALARMGUARD, INC.


                              By: /s/David Heidecorn
                                   Name: David Heidecorn
                                   Title:


                              THE GUARANTORS:
                              SECURITY SYSTEMS HOLDINGS, INC.


                              By: /s/ David Heidecorn
                                   Name: David Heidecorn
                                   Title:


                              ALARMGUARD HOLDINGS, INC.
                              (formerly known as Triton Holdings, Ltd.)


                              By: /s/ David Heidecorn
                                   Name: David Heidecorn
                                   Title:


                              THE LENDERS:
                              BANK OF BOSTON CONNECTICUT


                              By:
                                   Name:
                                   Title:

                              GENERAL ELECTRIC CAPITAL
                              CORPORATION


                              By:
                                   Name:
                                   Title:



                CONFIRMATION OF AND AMENDMENT TO
                 GUARANTEE AND PLEDGE AGREEMENT


   This CONFIRMATION OF AND AMENDMENT TO GUARANTEE AND PLEDGE
AGREEMENT (the "Agreement") is made as of this 22nd day of
August, 1997 by ALARMGUARD HOLDINGS, INC. (formerly Triton
Group, Ltd.), a Delaware corporation, with its chief executive
office located at 125 Frontage Road, Orange, Connecticut 06477
(the "Guarantor") in favor of BANK OF BOSTON CONNECTICUT, a
Connecticut savings bank, with its head office located at 100
Pearl Street, Hartford, Connecticut 06103 as Administrative
Agent (in such capacity, the "Administrative Agent") for the
banks, financial institutions and other lenders (the "Lenders")
which are or become parties to the Credit Agreement (as
hereinafter defined).

                      W I T N E S S E T H:

   Pursuant to that certain Second Amended and Restated Term
Loan and Acquisition Credit Agreement dated as of April 15, 1997
(as amended and in effect from time to time, the "Credit
Agreement"), by and among Alarmguard, Inc., a Delaware
corporation, with its chief executive office located at 125
Frontage Road, Orange, Connecticut 06477 (the "Borrower"),
Guarantor, Guarantor's wholly-owned subsidiary, Security Systems
Holdings, Inc., the Lenders, the Administrative Agent and
General Electric Capital Corporation as the documentation agent
for the Lenders (in such capacity, the "Documentation Agent"),
the Lenders have severally agreed to make loans, advances and
other extensions of credit to the Borrower upon the terms and
subject to the conditions set forth therein, to be evidenced by
the Notes issued by the Borrower thereunder.  In connection with
the execution and delivery of the Credit Agreement, and as a
condition precedent to the obligation of the Lenders to make
their respective loans, advances and other extensions of credit
to the Borrower under the Credit Agreement, Guarantor executed
and delivered a certain Guarantee Agreement dated as of April
15, 1997 to the Administrative Agent for the ratable benefit of
the Lenders (the "Guarantee").  In addition, in order to secure
its obligations under the Guarantee, Guarantor executed and
delivered a certain Pledge Agreement dated as of April 15, 1997
in favor of the Administrative Agent for the ratable benefit of
the Lenders (the "Pledge Agreement").

   Borrower, Guarantor, Security Systems Holdings, Inc., the
Lenders, the Administrative Agent and the Documentation Agent
have agreed to amend the Credit Agreement in certain respects
pursuant to a certain First Amendment to Second Amended and
Restated Term Loan and Acquisition Credit Agreement of even date
herewith (the "First Amendment").  A condition precedent to the
obligations of the Lenders under the First Amendment is the
execution and delivery of this Agreement by Guarantor for the
purpose of confirming and amending the Guarantee and the Pledge
Agreement to reflect the terms and conditions of the First
Amendment.

   NOW, THEREFORE, in consideration of the premises and to
induce the Administrative Agent, the Documentation Agent and the
Lenders to enter into the First Amendment and to induce the
Lenders to continue to make their respective loans to the
Borrower under the Credit Agreement, the Guarantor hereby agrees
with the Administrative Agent, for the ratable benefit of the
Lenders as follows:

   1.     Guarantee.  Guarantor hereby agrees, notwithstanding
the amendment of the Credit Agreement pursuant to the First
Amendment, that the Guarantee and its agreements, covenants,
obligations, representations and warranties thereunder and
therein, are hereby expressly ratified, confirmed, restated and,
to the extent necessary, amended as of the date hereof so that
the term "Credit Agreement," as used in the Guarantee, shall
mean the Credit Agreement, as amended by the First Amendment and
as such may be amended, extended, restated or renewed from time
to time in the future.

   2.     Pledge Agreement.  Guarantor hereby agrees,
notwithstanding the amendment of the Credit Agreement pursuant
to the First Amendment, that the Pledge Agreement and its
agreements, covenants, obligations, representations and
warranties thereunder and therein, and the grant of the pledges,
liens and other encumbrances thereby, are hereby expressly
ratified, confirmed, restated and, to the extent necessary,
amended as of the date hereof so that the term "Credit
Agreement," as used in the Pledge Agreement, shall mean the
Credit Agreement, as amended by the First Amendment and as such
may be amended, extended, restated or renewed from time to time.

   In addition, the Pledge Agreement is hereby amended as
   follows:

   (a)         Schedule 1 to the Pledge Agreement is hereby
deleted in its entirety and Schedule 1 to this Agreement is
hereby substituted in lieu thereof as of the date hereof.

   (b)         Section 6 of the Pledge Agreement is hereby
deleted in its entirety and the following is hereby substituted
in lieu thereof:

     6.   Cash Dividends: Voting Rights.  Unless an Event of
     Default shall have occurred and be continuing and the
     Administrative Agent shall have given notice to the Pledgor
     of the Administrative Agent's intent to exercise its
     corresponding rights pursuant to paragraph 7 below, the
     Pledgor shall be permitted, except as hereinafter provided,
     to receive all cash dividends paid in the normal course of
     business of the Issuer and consistent with past practice,
     to the extent permitted in the Credit Agreement, in respect
     of the Pledged Stock and to exercise all voting and
     corporate rights with respect to the Pledged Stock,
     provided, however, that no vote shall be cast or corporate
     right exercised or other action taken which would impair
     the Collateral or which would be inconsistent with or
     result in any violation of any provision of the Credit
     Agreement, the Notes, the Other Documents or this Pledge
     Agreement.  Notwithstanding the foregoing, the Pledgor
     shall direct Mission West Properties to pay any cash
     dividend to be paid to the Pledgor to the Administrative
     Agent in accordance with instructions provided by the
     Administrative Agent.

     (c)  The following is hereby added as a new sentence in
Section 18 of the Pledge Agreement.

                    Notwithstanding the foregoing, all notices
          to Mission West Properties shall be given as follows:

          Mission West Properties
          6815 Flanders Drive
          Suite 250
          San Diego, California 92121-3914
          Attn:     Michael M. Earley, President

   3.     Governing Law.  This Agreement shall be construed and
enforced in accordance with and governed by the laws of the
State of Connecticut.

   4.     Counterparts.  This Agreement may be executed in any
number of counterparts and by different parties on different
counterparts, each of which when so executed and delivered shall
be an original, but all of which shall together constitute one
and the same instrument.

   5.     Successors and Assigns.  This Agreement shall be
binding upon and inure to the benefit of the parties hereto and
their respective successors and assigns.

   IN WITNESS WHEREOF, Guarantor has executed this Agreement as
of the date first above written.

                            ALARMGUARD HOLDINGS, INC.
                            
                            
                            By: /s/ David Heidecorn
                              Name David Heidecorn
                              Title:

The foregoing is hereby consented to and acknowledged as of this
22nd day of August, 1997.


                              BANK OF BOSTON CONNECTICUT
                              (as Administrative Agent)


                              By: /s/ Mark St. Pierre
                                   Name: Mark St. Pierre
                                   Title:   Assistant Vice President


                          SCHEDULE 1 to
                        Pledge Agreement


                  DESCRIPTION OF PLEDGED STOCK

  100 shares of Common Stock, $.0l par value issued by Security
                    Systems Holdings, Inc., a
                      Delaware corporation


 676,000 shares of Common Stock, no par value issued by Mission
                  West Properties, a California
                           corporation