Citizens Bank
                                                  Citizens Bank of Massachusetts
                                        Exchange Place, 53 State Street Building
                                                                Boston, MA 02109


                                        January 23, 2002

Turbotec Products, Inc.
651 Day Hill Road
Windsor, CT 06095
Attn:    Robert I. Lieberman, President

Gentlemen:

      Reference is made to our Amended and Restated Loan and Security Agreement
(Accounts Receivable and Inventory) dated October 31, 1994, together with all
amendments and additions thereto (hereinafter called the "Agreement").
Notwithstanding the provisions of the Agreement, it is agreed, effective as of
November 1, 2000, that the Agreement shall be amended as follows:

      1. Section 5.A of the Agreement is hereby stricken in its entirety and the
following new Section 5.A substituted therefor:

            "A. Subject to the terms and provisions of this Agreement, the Bank
      hereby establishes a discretionary revolving line of credit in Borrower's
      favor in the amount set forth below, as determined by Bank from time to
      time hereafter. Bank may make such loans to Borrower, based upon such
      facts and circumstances existing at the time of the request, as from time
      to time Bank elects to make which are secured by Borrower's Inventory,
      Accounts and all other Collateral and the proceeds thereof. Without
      limiting the discretionary nature of Bank's obligation to make loans
      hereunder, or the demand feature of any loans that Bank does make
      hereunder, Borrower agrees that the aggregate unpaid principal of all
      loans outstanding at any one time shall not exceed the Borrowing Base. The
      term "Borrowing Base" as used herein shall mean the sum of the following:

            (a) up to eighty (80%) percent of the unpaid face amount of
      Qualified Accounts (as defined below) or such other percentage thereof as
      may from time to time be fixed by the Bank upon notice to Borrower, PLUS

            (b) the lesser of (i) $1,200,000.00, or (ii) up to (A) fifty (50%)
      percent of the cost or market value, whichever is lower, of all Eligible
      Inventory (as defined below) consisting of raw materials and twisted
      tubes, plus (B) the lesser of (1) $350,000.00, or (2) fifty (50%) percent
      of the cost or market value, whichever is lower, of all Eligible Inventory
      consisting of finished goods, MINUS

            (c) one hundred (100%) percent of the aggregate amount then undrawn
      on all letters of credit and acceptances issued by the Bank for the
      account of the Borrower;

      but in no event shall the sum of all direct loans plus the sum of the
      aggregate amount undrawn on all letters of credit and acceptances be in
      excess of $2,400,000.00 (the "Credit Limit") or such other sum as may from
      time to time be fixed by the Bank upon notice to Borrower. All such loans
      shall bear interest and at the option of Bank shall be evidenced by demand
      notes in form satisfactory to Bank, but in the absence of notes shall be
      conclusively evidenced by the Bank's record of disbursements and
      repayments and shall be payable ON DEMAND.

            (d) All loans made by Bank pursuant to this Section 5 shall bear
      interest and, at the option of Bank, shall be evidenced by and repayable
      in accordance with a revolving demand note drawn to the order of Bank
      substantially the form of Exhibit 1 hereto (the "Note"), as the same may
      hereafter be amended, supplemented or restated from time to time and any
      note or notes issued in substitution therefor, but in the absence of the
      Note shall be conclusively evidenced by Bank's records of loans and
      repayments and shall be payable on demand.


<PAGE>


            Interest, net of those loans (if any) which bear interest calculated
      by reference to the LIBOR Rate (as defined below), will be charged to
      Borrower at a fluctuating rate which is the daily equivalent to a rate
      equal to the Prime Rate, or at such other rate agreed on from time to time
      by the parties, upon any balance owing to Bank at the close of each day
      and shall be payable on the first day of each month in arrears until the
      Bank makes demand. The rate of interest payable by Borrower shall be
      changed effective as of that date in which a change in the Prime Rate
      becomes effective. Interest shall be computed on the basis of the actual
      number of days elapsed over a year of three hundred sixty (360) days. The
      term "Prime Rate" as used herein and in any supplement and amendment
      hereto shall mean the per annum rate of interest announced from time to
      time by Bank at its offices in Boston, Massachusetts, as its Prime Rate
      (or if Bank ceases to announce a rate so designated, any similar successor
      rate designated by Bank), it being understood that such rate is a
      reference rate and not necessarily the lowest rate of interest charged by
      Bank. Interest shall be payable in lawful money of the United States of
      America to Bank, or as Bank shall direct, without set-off, deduction or
      counterclaim monthly, in arrears, on the first day of each month,
      commencing on the first day of the month next succeeding the date hereof.

      Interest, net of those loans (if any) which bear interest calculated by
      reference to the Prime Rate, will be charged to Borrower at a rate which
      is the equivalent to the LIBOR Lending Rate (as defined below) plus the
      Applicable Margin (as defined below).

      (e)   As used in this Agreement, the following terms shall have the
            following meanings:

            "Applicable Margin" shall mean three (3.0%) percent per annum (i.e.,
            300 basis points).

            "Borrowing Date" shall mean any day upon which a LIBOR Rate Loan is
            made.

            "Business Day" shall mean:

                  (i) any day which is neither a Saturday or Sunday nor a legal
            holiday on which commercial banks are authorized or required to be
            closed in Boston, Massachusetts;

                  (ii) when such term is used to describe a day on which a
            borrowing, payment, prepayment, or repayment is to be made in
            respect of any LIBOR Rate Loan, any day which is: (A) neither a
            Saturday or Sunday nor a legal holiday on which commercial banks are
            authorized or required to be closed in New York City; and (B) a
            London Banking Day; and

                  (iii) when such term is used to describe a day on which an
            interest rate determination is to be made in respect of any LIBOR
            Rate Loan, any day which is a London Banking Day.

            "Dollars" or "$" shall mean currency of the United States of
            America.

            "Eurodollars" shall mean Dollars acquired by Bank through the
            purchase or other acquisition of deposits denominated in Dollars and
            made with any bank or branch of a bank (including any branch of the
            Bank) located outside the United States of America.

            "Hedging Contracts" shall mean interest rate swap agreements,
            interest rate cap agreements and interest rate collar agreements, or
            any other agreements or arrangements entered into between Borrower
            and Bank designed to protect the Borrower against fluctuations in
            interest rates or currency exchange rates.


<PAGE>


            "Hedging Obligations" means, with respect to Borrower, all
            liabilities of Borrower to Bank under Hedging Contracts.

            "Interbank Market" shall mean, with respect to any LIBOR Rate Loan,
            any recognized interbank Eurodollar market chosen in good faith by
            Bank.

            "Interest Payment Date" shall mean, relative to any LIBOR Rate Loan,
            having an Interest Period of three months or less, the last Business
            Day of such Interest Period, and as to any LIBOR Rate Loan having an
            Interest Period longer than three months, each Business Day which is
            three months, or a whole multiple thereof, after the first day of
            such Interest Period and the last day of such Interest Period.

            "Interest Period" shall mean, relative to any LIBOR Rate Loans:

                  (i) initially, the period beginning on (and including) the
            date on which such LIBOR Rate Loan is made or continued as, or
            converted into, a LIBOR Rate Loan pursuant to this Agreement and
            ending on (but excluding) the day which numerically corresponds to
            such date one, two, or three months thereafter (or, if such month
            has no numerically corresponding day, on the last Business Day of
            such month), in each case as the Borrower may select in its notice
            pursuant to this Agreement; and

                  (ii) thereafter, each period commencing on the last day of the
            next preceding Interest Period applicable to such LIBOR Rate Loan
            and ending one, two or three months thereafter, as selected by the
            Borrower by irrevocable notice to the Bank not less than two
            Business Days prior to the last day of the then current Interest
            Period with respect thereto;

            provided, however, that

                  (i) the Borrower shall not be permitted to select Interest
            Periods to be in effect at any one time which have expiration dates
            occurring on more than five (5) different dates;

                  (ii) Interest Periods commencing on the same date for LIBOR
            Rate Loans comprising part of the same advance under this Agreement
            shall be of the same duration;

                  (iii) Interest Periods for LIBOR Rate Loans in connection with
            which Borrower has or may incur Hedging Obligations with the Bank
            shall be of the same duration as the relevant periods set under the
            applicable Hedging Contracts;

                  (iv) if such Interest Period would otherwise end on a day
            which is not a Business Day, such Interest Period shall end on the
            next following Business Day unless such day falls in the next
            calendar month, in which case such Interest Period shall end on the
            first preceding Business Day; and

                  (v) no Interest Period may end later than the termination date
            of this Agreement.

            "LIBOR Lending Rate" shall mean, relative to any LIBOR Rate Loan to
            be made, continued or maintained as, or converted into, a LIBOR Rate
            Loan for any Interest Period, a rate per annum determined pursuant
            to the following formula:


<PAGE>


                    LIBOR Lending Rate   =             LIBOR Rate
                                             -----------------------------------
                                             (1.00  -  LIBOR Reserve Percentage)

            "LIBOR Rate" shall mean, relative to any Interest Period for LIBOR
            Rate Loans, the offered rate for deposits of U.S. Dollars in an
            amount approximately equal to the amount of the requested LIBOR Rate
            Loan for a term coextensive with the designated Interest Period
            which the British Bankers' Association fixes as its LIBOR rate and
            which appears on the Telerate Page 3750 as of 11:00 a.m. London time
            on the day which is two London Banking Days (as defined below) prior
            to the beginning of such Interest Period.

            "LIBOR Rate Loan" shall mean, any loan or advance the rate of
            interest applicable to which is based upon the LIBOR Rate.

            "LIBOR Reserve Percentage" shall mean, relative to any day of any
            Interest Period for LIBOR Rate Loans, the maximum aggregate (without
            duplication) of the rates (expressed as a decimal fraction) of
            reserve requirements (including all basic, emergency, supplemental,
            marginal and other reserves and taking into account any transitional
            adjustments or other scheduled changes in reserve requirements)
            under any regulations of the Board of Governors of the Federal
            Reserve System (the "Board") or other governmental authority having
            jurisdiction with respect thereto as issued from time to time and
            then applicable to assets or liabilities consisting of "Eurocurrency
            Liabilities", as currently defined in Regulation D of the Board,
            having a term approximately equal or comparable to such Interest
            Period.

            "London Banking Day" shall mean a day on which dealings in US dollar
            deposits are transacted in the London Interbank Market.

            "Maturity Date" shall mean the date on which an Interest Period
            expires.

            "Prime Rate Loan(s)" shall mean, when used in the singular, any
            loans on which the interest rate is calculated by reference to the
            Prime Rate and, when used in the plural, shall mean all such loans.

            (e) Bank shall not be required to make a LIBOR Rate Loan, or convert
      a Prime Rate Loan into a LIBOR Rate Loan, unless Bank shall have received
      from the Borrower a request for such LIBOR Rate Loan, in the form of
      Exhibit 2 annexed hereto (herein a "Notice of Borrowing"). By delivering a
      borrowing request (i.e., Notice of Borrowing) to the Bank on or before
      10:00 a.m., New York time, on a Business Day, the Borrower may from time
      to time irrevocably request, on not less than two nor more than five
      Business Days' notice, that a LIBOR Rate Loan be made in a minimum amount
      of Five Hundred Thousand ($500,000.00) Dollars and integral multiples of
      One Hundred Thousand ($100,000.00) Dollars. On the terms and subject to
      the conditions of this Agreement, each LIBOR Rate Loan shall be made
      available to the Borrower no later than 11:00 a.m. New York time on the
      first day of the applicable Interest Period by deposit to the account of
      the Borrower as shall have been specified in its borrowing request.

            (f) After receipt from the Borrower of any Notice of Borrowing which
      requests a LIBOR Rate Loan, Bank shall determine if it is able to make
      such LIBOR Rate Loan (or if it is unable to do so for reasons described in
      this section only) and will notify the Borrower upon confirmation of its
      ability to do so. If Bank determines in good faith that, by reason of
      circumstances affecting the Interbank Market, adequate and reasonable
      methods do not exist for ascertaining the LIBOR Rate which would otherwise
      be applicable to such LIBOR Rate Loan, then Bank shall so notify the
      Borrower on or before 4:00 p.m. on the Business Day prior to the Borrowing
      Date specified in


<PAGE>


      the Notice of Borrowing, and in such event, Bank shall not be obligated to
      make such LIBOR Rate Loan and the Notice of Borrowing shall be deemed to
      have been withdrawn by the Borrower with Bank's consent and substituted
      with a request for a Prime Rate Loan in an amount equal to the requested
      LIBOR Rate Loan.

            (g) By delivering a continuation/conversion notice to the Bank on or
      before 10:00 a.m., New York time, on a Business Day, the Borrower may from
      time to time irrevocably elect, on not less than two nor more than five
      Business Days' notice, that all, or any portion in an aggregate minimum
      amount of Five Hundred Thousand ($500,000.00) Dollars and integral
      multiples of One Hundred Thousand ($100,000.00) of any LIBOR Rate Loan be
      converted on the last day of an Interest Period into a LIBOR Rate Loan
      with a different Interest Period, or continued on the last day of an
      Interest Period as a LIBOR Rate Loan with a similar Interest Period,
      provided, however, that no portion of the outstanding principal amount of
      any LIBOR Rate Loans may be converted to, or continued as, LIBOR Rate
      Loans when any default or Event of Default has occurred and is continuing,
      and no portion of the outstanding principal amount of any LIBOR Rate Loans
      may be converted to, LIBOR Rate Loans of a different duration if such
      LIBOR Rate Loans relate to any Hedging Obligations. In the absence of
      delivery of a continuation/conversion notice with respect to any LIBOR
      Rate Loan at least two Business Days before the last day of the then
      current Interest Period with respect thereto, such LIBOR Rate Loan shall,
      on such last day, automatically convert to a loan that accrues interest by
      reference to the Prime Rate.

            (h) Except as otherwise provided herein, any Notice of Borrowing
      which requests a LIBOR Rate Loan shall be irrevocable and binding upon the
      Borrower. In the event the Borrower fails to borrow the LIBOR Rate Loan
      requested on the Borrowing Date specified in such Notice of Borrowing, the
      Borrower shall indemnify Bank against any and all losses and expenses
      incurred by Bank by reason of such failure including, without limiting the
      generality of the foregoing, all losses and expenses incurred by reason of
      the liquidation, disposition or reemployment of deposits or other funds
      acquired by Bank to fund such LIBOR Rate Loan.

            (i) Interest on the outstanding principal amount of each LIBOR Rate
      Loan shall accrue during the Interest Period applicable thereto at a rate
      equal to the sum of the LIBOR Lending Rate for such Interest Period plus
      the Applicable Margin thereto and be payable on each Interest Payment
      Date.

            (j) LIBOR Rate Loans shall mature and become payable in full on the
      last day of the Interest Period relating to such LIBOR Rate Loan. Upon
      maturity, a LIBOR Rate Loan may be continued for an additional Interest
      Period or may be converted to a Prime Rate Loan, as set forth above.

            (k) LIBOR Rate Loans may be prepaid on the terms and conditions set
      forth herein. For LIBOR Rate Loans in connection with which the Borrower
      has or may incur Hedging Obligations, additional obligations may be
      associated with prepayment in accordance with the terms and conditions of
      the applicable Hedging Contracts. The Borrower shall give the Bank, no
      later than 10:00 a.m., New York City time, at least four (4) Business Days
      notice of any proposed prepayment of any LIBOR Rate Loans, specifying the
      proposed date of payment of such LIBOR Rate Loans, and the principal
      amount to be paid. Each partial prepayment of the principal amount of
      LIBOR Rate Loans shall be in an integral multiple of Five Hundred Thousand
      ($500,000.00) Dollars and accompanied by the payment of all charges
      outstanding on such LIBOR Rate Loans and of all accrued interest on the
      principal repaid to the date of payment. Borrower acknowledges that
      prepayment or acceleration of a LIBOR Rate Loan during an Interest Period
      shall result in the Bank incurring additional costs, expenses and/or
      liabilities and that it is extremely difficult and impractical to
      ascertain the extent of such costs, expenses and/or liabilities.
      Therefore, all full or partial prepayments of LIBOR Rate Loans shall be
      accompanied by, and the Borrower hereby promises to pay, on each date a
      LIBOR Rate Loan is prepaid or the date all sums payable


<PAGE>


      hereunder become due and payable, by acceleration or otherwise, in
      addition to all other sums then owing, an amount ("LIBOR Rate Loan
      Prepayment Fee") determined by the Bank pursuant to the following formula:

            (i)   the then current rate for United States Treasury securities
                  (bills on a discounted basis shall be converted to a bond
                  equivalent) with a maturity date closest to the end of the
                  Interest Period as to which prepayment is made, subtracted
                  from

            (ii)  the LIBOR Lending Rate plus the Applicable Margin applicable
                  to the LIBOR Rate Loan being prepaid.

      If the result of this calculation is zero or a negative number, then there
      shall be no LIBOR Rate Loan Prepayment Fee. If the result of this
      calculation is a positive number, then the resulting percentage shall be
      multiplied by:

            (iii) the amount of the LIBOR Rate Loan being prepaid.

            The resulting amount shall be divided by:

            (iv)  360

            and multiplied by:

            (v)   the number of days remaining in the Interest Period as to
                  which the prepayment is being made.

      Said amount shall be reduced to present value calculated by using the
      referenced United States Treasury securities rate and the number of days
      remaining on the Interest Period for the LIBOR Rate Loan being prepaid.

      The resulting amount of these calculations shall be the LIBOR Rate Loan
      Prepayment Fee.

            (l) If the Bank shall determine (which determination shall, upon
      notice thereof to the Borrower be conclusive and binding on the Borrower)
      that the introduction of or any change in or in the interpretation of any
      law, rule, regulation or guideline (whether or not having the force of
      law), makes it unlawful, or any central bank or other governmental
      authority asserts that it is unlawful, for the Bank to make, continue or
      maintain any LIBOR Rate Loan as, or to convert any loan into, a LIBOR Rate
      Loan of a certain duration, the obligations of the Bank to make, continue,
      maintain or convert into any such LIBOR Rate Loans shall, upon such
      determination, forthwith be suspended until the Bank shall notify the
      Borrower that the circumstances causing such suspension no longer exist,
      and all LIBOR Rate Loans of such type shall automatically convert into
      Prime Rate Loans at the end of the then current Interest Periods with
      respect thereto or sooner, if required by such law or assertion.

            (m) If, due to payments made by the Borrower pursuant to this
      Agreement or due to the acceleration of the Obligations or due to any
      other reason, Bank receives payments of principal of any LIBOR Rate Loan
      prior to the Maturity Date for such LIBOR Rate Loan, the Borrower shall,
      upon demand by Bank, pay to Bank any amounts required to compensate Bank
      for any additional losses, costs or expenses which it may reasonably incur
      as a result of such payment, including, without limitation, any loss,
      costs or expenses incurred by reason of the liquidation or reemployment of
      deposits or other funds acquired by Bank to fund or maintain such LIBOR
      Rate Loans.

            (n) If the Bank shall have determined that


<PAGE>


            (i)   US dollar deposits in the relevant amount and for the relevant
                  Interest Period are not available to the Bank in the London
                  Interbank Market;

            (ii)  by reason of circumstances affecting the Bank in the London
                  Interbank Market, adequate means do not exist for ascertaining
                  the LIBOR Rate applicable hereunder to LIBOR Rate Loans of any
                  duration, or

            (iii) the LIBOR Rate no longer adequately reflects the Bank=s cost
                  of funding loans.

      Then, upon notice from the Bank to the Borrower, the obligations of the
      Bank to make or continue any loans as, or to convert any loans into, LIBOR
      Rate Loans of such duration shall forthwith be suspended until the Bank
      shall notify the Borrower that the circumstances causing such suspension
      no longer exist.

            (o) In addition to the LIBOR Rate Loan Prepayment Fee, the Borrower
      agrees to reimburse the Bank (without duplication) for any increase in the
      cost to the Bank, or reduction in the amount of any sum receivable by the
      Bank, in respect, or as a result of:

            (i)   any conversion or repayment or prepayment of the principal
                  amount of any LIBOR Rate Loans on a date other than the
                  scheduled last day of the Interest Period applicable thereto;

            (ii)  any loans not being made as LIBOR Rate Loans in accordance
                  with the borrowing request thereof;

            (iii) any LIBOR Rate Loans not being continued as, or converted
                  into, LIBOR Rate Loans in accordance with the
                  continuation/conversion notice thereof, or

            (iv)  any costs associated with marking to market any Hedging
                  Obligations that (in the reasonable determination of the Bank)
                  are required to be terminated as a result of any conversion,
                  repayment or prepayment of the principal amount of any LIBOR
                  Rate Loan on a date other than the scheduled last day of the
                  Interest Period applicable thereto;

      The Bank shall promptly notify the Borrower in writing of the occurrence
      of any such event, such notice to state, in reasonable detail, the reasons
      therefor and the additional amount required fully to compensate the Bank
      for such increased cost or reduced amount. Such additional amounts shall
      be payable by the Borrower to the Bank within five days of its receipt of
      such notice, and such notice shall, in the absence of manifest error, be
      conclusive and binding on the Borrower. The Borrower understands, agrees
      and acknowledges the following: (a) the Bank does not have any obligation
      to purchase, sell and/or match funds in connection with the use of LIBOR
      Rate as a basis for calculating the rate of interest on a LIBOR Rate Loan,
      (b) the LIBOR Rate may be used merely as a reference in determining such
      rate, and (c) the Borrower has accepted the LIBOR Rate as a reasonable and
      fair basis for calculating such rate, the LIBOR Rate Prepayment Fee, and
      other funding losses incurred by the Bank. Borrower further agrees to pay
      the LIBOR Rate Prepayment Fee and other funding losses, if any, whether or
      not the Bank elects to purchase, sell and/or match funds.

            (p) If on or after the date hereof the adoption of any applicable
      law, rule or regulation or guideline (whether or not having the force of
      law), or any change therein, or any change in the interpretation or
      administration thereof by any governmental authority, central bank or
      comparable agency charged with the interpretation or administration
      thereof, or compliance by the Bank with any request or directive (whether
      or not having the force of law) of any such authority, central bank or
      comparable agency:


<PAGE>


            (i)   shall subject the Bank to any tax, duty or other charge with
                  respect to its LIBOR Rate Loans or its obligation to make
                  LIBOR Rate Loans, or shall change the basis of taxation of
                  payments to the Bank of the principal of or interest on its
                  LIBOR Rate Loans or any other amounts due under this Agreement
                  in respect of its LIBOR Rate Loans or its obligation to make
                  LIBOR Rate Loans (except for the introduction of, or change in
                  the rate of, tax on the overall net income of the Bank or
                  franchise taxes, imposed by the jurisdiction (or any political
                  subdivision or taxing authority thereof) under the laws of
                  which the Bank is organized or in which the Bank's principal
                  executive office is located); or

            (ii)  shall impose, modify or deem applicable any reserve, special
                  deposit or similar requirement (including, without limitation,
                  any such requirement imposed by the Board of Governors of the
                  Federal Reserve System of the United States) against assets
                  of, deposits with or for the account of, or credit extended
                  by, the Bank or shall impose on the Bank or on the London
                  Interbank Market any other condition affecting its LIBOR Rate
                  Loans or its obligation to make LIBOR Rate Loans;

      and the result of any of the foregoing is to increase the cost to the Bank
      of making or maintaining any LIBOR Rate Loan, or to reduce the amount of
      any sum received or receivable by the Bank under this Agreement with
      respect thereto, by an amount deemed by the Bank to be material, then,
      within fifteen (15) days after demand by the Bank, the Borrower shall pay
      to the Bank such additional amount or amounts as will compensate the Bank
      for such increased cost or reduction.

            (q) All payments by the Borrower of principal of, and interest on,
      the LIBOR Rate Loans and all other amounts payable hereunder shall be made
      free and clear of and without deduction for any present or future income,
      excise, stamp or franchise taxes and other taxes, fees, duties,
      withholdings or other charges of any nature whatsoever imposed by any
      taxing authority, but excluding franchise taxes and taxes imposed on or
      measured by the Bank's net income or receipts (such non-excluded items
      being called "Taxes"). In the event that any withholding or deduction from
      any payment to be made by the Borrower hereunder is required in respect of
      any Taxes pursuant to any applicable law, rule or regulation, then the
      Borrower will

            (i)   pay directly to the relevant authority the full amount
                  required to be so withheld or deducted;

            (ii)  promptly forward to the Bank an official receipt or other
                  documentation satisfactory to the Bank evidencing such payment
                  to such authority; and

            (iii) pay to the Bank such additional amount or amounts as is
                  necessary to ensure that the net amount actually received by
                  the Bank will equal the full amount the Bank would have
                  received had no such withholding or deduction been required.

      Moreover, if any Taxes are directly asserted against the Bank with respect
      to any payment received by the Bank hereunder, the Bank may pay such Taxes
      and the Borrower will promptly pay such additional amount (including any
      penalties, interest or expenses) as is necessary in order that the net
      amount received by the Bank after the payment of such Taxes (including any
      Taxes on such additional amount) shall equal the amount the Bank would
      have received had not such Taxes been asserted.

      If the Borrower fails to pay any Taxes when due to the appropriate taxing
      authority or fails to remit to the Bank the required receipts or other
      required documentary evidence, the Borrower shall indemnify the Bank for
      any incremental Taxes, interest or penalties that may become payable by
      the Bank as a result of any such failure.


<PAGE>


            (r) Notwithstanding anything to the contrary contained herein, Bank
      and Borrower agree that after the occurrence of an Event of Default which
      is continuing, Borrower shall not request and Bank will not make LIBOR
      Rate Loan."

      2. Section 12(d) of the Agreement is hereby stricken in its entirety and
the following new Section 12(d) substituted therefor:

      "(d) On the second business day of each week, Borrower shall furnish to
      Bank a certificate describing all of Borrower's Inventory by value based
      on the lower of cost or market value, listing all Inventory by nature,
      quantity and location, together with such other information as Bank may
      require."

      3. The following new Section 14(k) is hereby added to the Agreement:

            "(k) (Minimum Debt Service Coverage Ratio) permit, on a consolidated
      basis with Thermodynetics, Inc., its cash flow for the twelve (12) month
      period ending on the last day of each fiscal year of Borrower to be less
      than (i) one hundred (100%) percent of its debt service for the twelve
      (12) month period ending March 31, 2002 and (ii) one hundred fifteen
      (115%) percent of its debt service for the twelve (12) month period ending
      March 31, 2003 and thereafter."

      4. The following new definitions are hereby added to Section 14 of the
Agreement:

      "'cash flow' shall mean the sum of earnings before interest and taxes,
      plus depreciation and amortization, minus cash taxes paid in the
      applicable period, minus permitted dividends, minus $200,000.00 in
      maintenance capital expenditures; "debt service" shall mean the sum of
      current maturities of all long term debt plus all interest expense."

      Kindly note that the alterations contained herein do not in any way alter,
release or change any other sections contained in the Agreement.

      Please acknowledge your agreement to the foregoing by signing the enclosed
copy of this letter and returning the same to the undersigned.

                                        Very truly yours,

                                        CITIZENS BANK OF MASSACHUSETTS
                                        (Successor to USTrust)


                                        By:       /s/ James H. Herzog, Jr.
                                           ------------------------------------
                                           James H. Herzog, Jr., Vice President


UNDERSTOOD AND AGREED TO:

TURBOTEC PRODUCTS, INC.


By:    /s/ Robert I. Lieberman
   ------------------------------
   Robert I. Lieberman, President


<PAGE>


                         EXHIBIT 1 (of Exhibit 10 (iii)

                         CITIZENS BANK OF MASSACHUSETTS

                              REVOLVING DEMAND NOTE

$2,400,000.00                                              Boston, Massachusetts
                                                               January ___, 2002

      For value received, the undersigned, Turbotec Products, Inc., a
Massachusetts corporation (the "Borrower"), hereby promises to pay ON DEMAND,
and if demand is not sooner made, then as provided in the Loan Agreement
(defined below), to the order of Citizens Bank of Massachusetts, a Massachusetts
bank (the "Bank"), at its main office in Boston, Massachusetts, or at any other
place designated at any time by the holder hereof, in lawful money of the United
States of America and in immediately available funds, the principal sum of Two
Million Four Hundred Thousand ($2,400,000.00) Dollars or, if less, the aggregate
unpaid principal amount of all loans made by the Bank to the Borrower under the
Loan Agreement, together with interest on the principal amount hereunder
remaining unpaid from time to time, computed on the basis of the actual number
of days elapsed and a 360-day year, from the date hereof until this Note is
fully paid at the rate(s) from time to time in effect under the Amended and
Restated Loan and Security Agreement (Accounts Receivable and Inventory) dated
October 31, 1994, as amended (the "Loan Agreement") by and between the Bank and
the Borrower. The principal hereof and interest accruing thereon shall be due
and payable as provided in the Loan Agreement.

      This Note may be prepaid only in accordance with the Loan Agreement.

      This Note is issued pursuant, and is subject, to the Loan Agreement, which
provides, among other things, for acceleration hereof. This Note is the "Note"
referred to in the Loan Agreement.

      This Note is secured, among other things, pursuant to the Loan Agreement,
and may now or hereafter be secured by one or more other security agreements,
mortgages, deeds of trust, assignments or other instruments or agreements.

      The Borrower hereby agrees to pay all costs of collection, including
attorneys' fees and legal expenses in the event this Note is not paid when due,
whether or not legal proceedings are commenced.

      Presentment or other demand for payment, notice of dishonor and protest
are expressly waived. All rights and obligations hereunder shall be governed by
the laws of the Commonwealth of Massachusetts and this Note shall be deemed to
be under seal.

                                        By:
                                           -------------------------------------


<PAGE>


                         EXHIBIT 2 (of Exhibit 10 (iii)

                               NOTICE OF BORROWING

                                                        Date: ___________, 200__

To:   Citizens Bank of Massachusetts
      53 State Street
      Boston, Massachusetts 02109


      Re:   Amended and Restated Loan and Security Agreement (Accounts
            Receivable and Inventory) dated October 31, 1994, as amended (the
            "Loan Agreement") between Citizens Bank of Massachusetts (the
            "Bank") and Turbotec Products, Inc. (the "Borrower")

      This Notice of Borrowing confirms the following request for [ ] a LIBOR
      Rate Loan - [ ] conversion of a Prime Rate Loan (check applicable box)
      under the Loan Agreement.

      Date of Request:


      Date of LIBOR Rate Loan:


      Amount of LIBOR Rate Loan at LIBOR Rate: *


      Interest Period:

            1, 2 or 3 months

      [ ]   This is a request for a continuation/conversion of a LIBOR loan
            described as follows:

            Date of Original Loan:

            Amount of Original Loan:

            Maturity Date:

            Interest Period:

            Amount of Loan to be Continued or Converted:

The Borrower hereby certifies that all representations and warranties contained
in the Loan Agreement are true and accurate in all material respects on the date
of this Notice of Borrowing as though such representations and warranties had
been made on this date (except to the extent that such representation or
warranty expressly relates to an earlier date).

      Terms used herein which are defined in the Loan Agreement are used as so
defined.


                                        By:
                                           -------------------------------------

                       o   Minimum of $500,000.00 with increments of $100,000.00


<PAGE>


                         EXHIBIT 3 (of Exhibit 10 (iii)

                             COMPLIANCE CERTIFICATE

      Turbotec Products, Inc. ("Borrower") hereby certifies to Citizens Bank of
Massachusetts ("Bank"), pursuant to the Amended and Restated Loan and Security
Agreement (Accounts Receivable and Inventory) between Borrower and Bank dated
October 31, 1994 as may be amended from time to time ("Loan Agreement"), that:

A.    General

      1. Capitalized terms not defined herein shall have the meanings set forth
in the Loan Agreement.

      2. The Borrower has complied with all the terms, covenants and conditions
to be performed or observed by the Borrower contained in the Loan Agreement and
other documents required to be executed by the Borrower in connection with the
Loan Agreement.

      3. Neither on the date hereof nor, if applicable, after giving effect to
the loan made on the date hereof, does there exist an Event of Default or an
event which would with notice or the lapse of time, or both, constitute an Event
of Default.

      4. The representations and warranties contained in the Loan Agreement and
in any certificate, document or financial or other statement furnished at any
time thereunder are true, correct and complete in all material respects with the
same effect as though such representations and warranties had been made on the
date hereof, except to the extent that any such representation and warranty
relates solely to an earlier date (in which case such representation and
warranty shall be true, correct and complete on and as of such earlier date).

B.    Financial Covenants

      As of the date hereof or, for such period as may be designated below, the
computations, ratios and calculations as set forth below in accordance with
Section 15 of the Loan Agreement are true and correct:

      1.    Cash Flow Coverage Ratio - Section 14(k)

            The cash flow of the Borrower for the preceding twelve-month period
      was equal to ______ times the amount of the Borrower's fixed charges for
      such period, computed as follows:

            A.   EBITDA  ...........................................$___________

            B.   Cash taxes paid ...................................$___________

            C.   Permitted dividends ...............................$___________

            D.   $200,000 maintenance capital expenditures .........$___________

            E.   A - B - C - D = cash flow  ........................$___________

            F.   Interest  .........................................$___________

            G.   CMLTD  ............................................$___________

            H.   F + G = fixed charges .............................$___________

            I.   Ratio of E to H = ____ to _____

            Required:   Not less than 1.0 to 1 for the 12-month period ending
                          March 31, 2002
                        Not less than 1.15 to 1 for the 12-month period ending
                          March 31, 2003 and thereafter


<PAGE>


      IN WITNESS WHEREOF, the undersigned, a duly authorized officer of
Borrower, has executed and delivered this Certificate in the name and on behalf
of the Borrower on _________________, 200__.

                                                TURBOTEC PRODUCTS, INC.


                                                By:
                                                   -----------------------------