<PAGE>
                                                                     EXHIBIT 4.3


                            [FORTIS BANK LETTERHEAD]



Kwanasia Electronics Company Limited
Unit 605, Hong Leong Industrial Complex,
4 Wang Kwong Road,
Kowloon Bay,
Kowloon.

Date      23 February 2004
Ref.      KEM-2/KA/CRA
Subject   General Banking Facilities

Dear Sirs,

We refer to our recent discussion and are pleased to confirm that subject to
execution of satisfactory documentation we agree to revise your general banking
facilities under the following terms and conditions:-

IMPORT FACILITIES

Limit:     HKD5,000,000.- for the opening of letters of credit on such terms and
           conditions as we may from time to time stipulate, the delivery of
           goods against signing of trust receipts, invoice trust receipts, the
           negotiation of letters of credit under letters of guarantee, advances
           against export documents and/or discounting of invoices (upto 80%,
           maximum of 90 days) from restricted buyers listed below. In-house
           bills with related companies, including but not limited to Jetcrown
           Industrial Ltd, Deswell Industries Inc, and Kwanta Precision Metal
           Products Co Ltd, are not allowed.

           Invoice Trust Receipts facilities can be drawn against invoices from
           approved suppliers with payment made directly to their accounts.

           Invoice Discounting buyers' list

           1)    Huacomm Telecommunications Engineering (HK) Ltd.

           2)    One Link Information Ltd.

           3)    Harbour Networks Ltd.

           4)    Beijing Harbour Networks Co. Ltd.

           5)    Huawei Technologies Co. Ltd.

           6)    Huawei Tech. Investment Co. Ltd.

Please note that the maximum period for repayment of Drafts, Trust Receipts and
Invoice Trust Receipts is 90 days. For HKD bills, interest will be charged at
our Hong Kong Interbank Offered Rate OR our prevailing funding cost, whichever
is higher, plus 2%; for foreign currency bills, interest will be charged at our
London Interbank Offered Rate OR our prevailing funding cost, whichever is
higher, plus 2%. All rates subject to fluctuation at our discretion.

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                                                              [FORTIS BANK LOGO]


Date     23 February 2004
Subject  General Banking Facilities
         Kwanasia Electronics Company Limited
Pages    2/5

         L/C opening commission:
         On first USD50,000.-                       1/4%
         From USD50,001 to USD 150,000.-            1/12%
         On balance                                 1/24%

         Standby L/C commission: (on monthly basis)
         On first USD50,000.-                       1/8%
         On balance                                 1/16%

         In lieu of exchange commission:            1/8%

         Invoice Discounting Commission:            1/8% flat (minimum HKD300.-)

         Invoice T/R Commission:                    1/8% flat (minimum HKD300.-)

         Handling commission on:-
         Outwards Remittance                     HKD150.- flat on 1 or 2  cables
         Inward Remittance via T/T               HKD50.- flat

         OVERDRAFT FACILITIES

         (Sublimit of the above trade limit of HKD5,000,000.-)
         Limit:          HKD2,000,000.-
         Interest:       Payable monthly and to be reduced to our HKD Prime Rate
                         OR our prevailing funding cost, whichever is higher,
                         all rates subject to fluctuation at our discretion.

         STANDBY LETTER OF CREDIT ISSUED ON YOUR BEHALF

         (Sublimit of the above overdraft limit of HKD2,000,000.-)
         L/C Amount      HKD1,000,000.-
         Tenor :         12 months maximum

         SHORT-TERM LOAN FACILITIES

         (Sublimit of the above overdraft limit of HKD2,000,000.-)
         Amount:         HKD2,000,000.-
                         Short-Term loan is to be drawn from time to time in
                         minimum of HKD1,000,000.- and in multiples of
                         HKD500,000.- for the periods of one month, two months
                         and three months maximum.
         Interest:       For HKD currency loan amount, interest will be charged
                         at our Hong Kong Interbank Offered Rate OR our
                         prevailing funding cost, whichever is higher, plus 2%,
                         payable monthly. For foreign currency loan amount,
                         interest will be charged at our London Interbank
                         Offered Rate OR our prevailing funding cost, whichever
                         is higher, plus 2%, payable monthly. All rates subject
                         to fluctuation at our discretion.

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                                                              [FORTIS BANK LOGO]


Date        23 February 2004
Subject     General Banking Facilities
            Kwanasia Electronics Company Limited
Pages       3/5

            Unless otherwise specified, interest on the above facilities is
            calculated on a daily basis and on the basis of a 365-day year for
            Hong Kong Dollars and 360-day year for United States Dollars
            denominated facilities (same for ordinary and leap years).

            Any amount unpaid on due date will be subject to additional interest
            at the Bank's then prevailing overdue interest rate and will be
            compounded monthly. We may, without prejudice to our rights,
            increase the interest rate on the entire outstanding if any amount
            becomes overdue.

            Whilst the aforesaid facilities are outstanding, all the goods held
            to our order in relation to such facilities will be insured in such
            amount as we may in our discretion so stipulate.

            An annual facilities fee of HKD5,000.- p.a. (subject to revision at
            our discretion) will be charged to your current account in
            November starting from 2004, which is non-refundable.

            As securities, we are presently holding the charge dated 15 November
            2001 which you have duly executed in our favour of all monies in the
            deposit accounts with us in your name. Your current deposit of not
            less than HKD1,001,306.39 or its equivalent in USD (or its 110%
            equivalent in other currencies acceptable to us) together with
            interest accrued thereon with us is, for the avoidance of doubt,
            subject to this charge.

            Please note that we are agreeable to revise the above facilities
            package with Import Facilities increased to HKD10,000,000.- and the
            sublimit of overdraft, standby L/C and short-term loan facilities
            increased to HKD3,000,000.- in aggregate subject to the execution of
            a letter of corporate guarantee for HKD10,000,000.- by Deswell
            Industries Inc. which we enclose herewith for signature and return.

            As additional support for the aforesaid facilities, yourgoodselves,
            Deswell Industries Inc. and Mr. Lee Shu Kwan and Mr. Tam Man
            Chi have undertaken that :-

            a)    Deswell Industries Inc. will not give corporate guarantee to
                  any financial institutions or banks for the account of your
                  Company unless with our prior written consent;

            b)    Mr. Lee Shu Kwan and Mr. Tam Man Chi will not give personal
                  guarantee to any financial institutions or banks for the
                  account of your Company unless with our prior written consent;

            c)    you will immediately notify us of any change of directorship
                  or shareholdership or any amendment of the Memorandum and
                  Articles of Association of your Company; and

            d)    you will channel through us an annual bills turnover of not
                  less than HKD18 Million.

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                                                              [FORTIS BANK LOGO]


Date        23 February 2004
Subject     General Banking Facilities
            Kwanasia Electronics Company Limited
Pages       4/5

            If you have provided to us the Sharing of Credit Data - Customer
            Consent Form, whether in connection with the above facilities or
            otherwise, you are reminded of the acknowledgement, agreement and
            consent therein contained, in particular but without limitation, our
            right to terminate the above and any or all other facilities and
            financial accommodation upon your giving notice to revoke the
            consent given.

            We reserve the overriding right to (a) demand immediate repayment of
            any or all of the amount outstanding in respect of the facilities
            together with all accrued interest and other moneys payable and (b)
            revise the terms and conditions applicable to the facilities or
            withdraw the facilities, in each case at any time at our discretion.

            Without prejudice to any of the provisions herein, all moneys
            outstanding hereunder will automatically become immediately due
            and payable on our receipt of any claim or notice of any interest by
            any third party (including without limitation notice to recover any
            amount under any Ordinance, garnishee order nisi, assignment or any
            security interest) affecting any of our liabilities to you or any
            other party who has provided any guarantee or other security in
            respect of your obligations to us.

            We may, without prior notice, at any time (irrespective of whether
            there is any default in payment of any sum payable hereunder) set
            off any of our liabilities (in any currency, wherever situated or
            payable, and whether or not matured) to you against any liabilities
            owed by you to us whether your liabilities be actual or contingent,
            present or future, or primary or collateral. Your liabilities in
            each case include without limitation joint liabilities. For this
            purpose, we may use all or any part of such liabilities to buy such
            other currencies as may be necessary to effect such set off at our
            spot rate. If any such liabilities is unliquidated or unascertained,
            we may set off the estimated amount (determined by us at our
            discretion) of such liability. Nothing in this provision is intended
            to give us any security of proprietary interest whether by way of
            mortgage, charge or otherwise. This provision operates by way of
            contract and self-help remedies.

            Please note that by signing and returning to us a copy of this
            letter, you are consenting to our providing to any guarantor or
            provider of security in respect of any loan or credit facilities
            extended or to be extended to you (including without limitation the
            above facilities) or the professional advisers of such guarantor or
            provider of security all information (including financial
            information relating to or provided by you) concerning any or all
            loans and credit facilities extended or to be extended to you
            including without limitation the following:

            (a)   a copy of the contract evidencing the obligations to be
                  guaranteed or secured or a summary thereof;

            (b)   a copy of any formal demand for overdue payment which is sent
                  to you after you have failed to settle an overdue amount
                  following a customary reminder; and

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                                                              [FORTIS BANK LOGO]


Date        23 February 2004
Subject     General Banking Facilities
            Kwanasia Electronics Company Limited
Pages       5/5

            (c)   from time to time on request by the guarantor or provider of
                  security, a copy of the latest statement of account provided
                  to you.

            To keep our file updated, you are required to:-

            i)    provide us with your audited financial statements within six
                  months from the end of each financial year; and

            ii)   immediately inform us of any change of your directors or
                  amendment of your constitutional documents and provide us with
                  the documents or information in relation to the same upon our
                  demand.

            This facility letter shall be governed by and construed in
            accordance with the laws of the Hong Kong Special Administrative
            Region. You will irrevocably submit to the non-exclusive
            jurisdiction of the Courts of the Hong Kong Special Administrative
            Region.

            Kindly signify your agreement to the foregoing by returning to us,
            duly signed, the enclosed duplicate of this letter. If no signed
            confirmation is received from you within one month from the date of
            this letter or if after you have returned to us on time the signed
            duplicate of this letter, the facilities (or the revised part where
            applicable) are not drawn down within three months from the date
            hereof, the facilities may be treated as cancelled at our absolute
            discretion.

            Yours faithfully,

            For FORTIS BANK ASIA HK

            /s/ [ILLEGIBLE]

            We agree to the terms and conditions set out above. We give our
            express consent to your providing to any guarantor or provider of
            security in respect of any loan or credit facilities extended to us
            or the professional advisers of such guarantor or provider of
            security the information referred to above.

            For and on behalf of
            KWANASIA ELECTRONICS CO. LTD.
            /s/ [ILLEGIBLE]
            ------------------------------
            Authorised Signature(1)

            Kwanasia Electronics Company Limited
            Date:

            c.c. 20/02/04
            -/lc