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                                                                     Exhibit 4.5
                                   AROC INC.

                           OFFER TO PURCHASE FOR CASH
                   ALL OUTSTANDING SHARES OF ITS COMMON STOCK
                                    FOR CASH
                   AT A PURCHASE PRICE OF $0.06 NET PER SHARE

THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY
TIME ON JUNE 12, 2001 (THE "EXPIRATION DATE"), UNLESS THE OFFER IS EXTENDED.
EXTENDED.
                                  May 14, 2001

To Our Clients:

     Enclosed for your consideration are an Offer to Purchase, dated May 14,
2001 (the "Offer to Purchase"), and a related Letter of Transmittal in
connection wit the offer by Aroc Inc., a Delaware corporation (the "Company") to
purchase for cash any and all outstanding shares of its common stock, $0.001 par
value per share (the "Shares"), of the Company at a price of $0.06 per Share,
net to the seller in cash, upon the terms and subject to the conditions set
forth in the Offer to Purchase and in the related Letter of Transmittal (which,
together with the Offer to Purchase and any amendments or supplements hereto or
thereto, collectively, constitute the "Offer").

     We are (or our nominee is) the holder of record of Shares held by us for
your account.  A TENDER OF SUCH SHARES CAN BE MADE ONLY BY US OR OUR NOMINEE AS
THE HOLDER OF RECORD AND PURSUANT TO YOUR INSTRUCTIONS.  THE LETTER OF
TRANSMITTAL IS FURNISHED TO YOU FOR YOUR INFORMATION ONLY AND CANNOT BE USED BY
YOU TO TENDER SHARES HELD BY US FOR YOUR ACCOUNT.

     We request instructions as to whether you wish to have us tender on your
behalf any or all of the Shares held by us for your account, upon the terms and
subject to the conditions set forth in the Offer.

     Your attention is invited to the following:

          1.  The tender price is $0.06 per Share, net to the seller in cash;

          2.  The Offer is being made for any and all outstanding Shares;

          3.  A special committee of the Board of Directors (the "Special
     Committee"), consisting of the sole independent director, has determined
     that the Offer is fair to the unaffiliated stockholders of the Company.
     The Special Committee recommends that the unaffiliated stockholders accept
     the offer and tender their Shares pursuant to the Offer;

          4.  The Offer and withdrawal rights will expire at 12:00 Midnight, New
     York City time, on June 12, 2001, 2001, unless the Offer is extended; and
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          5.  Tendering stockholders will not be obligated to pay brokerage
     fees, commissions or stock transfer taxes, except as otherwise provided in
     Instruction 6 of the Letter of Transmittal, with respect to the purchase of
     Shares by the Company pursuant to the Offer.  However, federal income tax
     backup withholding at a rate of 31% may be required, unless an exemption is
     provided or unless the required taxpayer identification information is
     provided.  See Instruction 9 of the Letter of Transmittal.

     If you wish to have us tender any or all of your Shares, please so instruct
us by completing, executing and returning to us the instruction form contained
in this letter.  An envelope in which to return your instructions to us is
enclosed.  If you authorize the tender of your Shares, all such Shares will be
tendered unless otherwise specified in your instructions.  YOUR INSTRUCTIONS
SHOULD BE FORWARDED TO US IN AMPLE TIME TO PERMIT US TO SUBMIT A TENDER ON YOUR
BEHALF PRIOR TO THE EXPIRATION OF THE OFFER.

     The Offer is made solely by the Offer to Purchase and the related Letter of
Transmittal and is being made to all holders of Shares.  The Company is not
aware of any state where the making of the Offer is prohibited by administrative
or judicial action pursuant to any valid state statute.  If the Company becomes
aware of any valid state statute prohibiting the making of the Offer or the
acceptance of Shares pursuant thereto, the Company will make a good faith effort
to comply.  If after such good faith effort, the Company cannot comply with such
state statute, the Offer will not be made to (nor will tenders be accepted from
or on behalf of) the holders of Shares in such state.  In any jurisdiction where
the securities, blue sky or other laws require the Offer to be made by a
licensed broker or dealer, the Offer shall be deemed to be made on behalf of the
Company by one or more registered brokers or dealers licensed under the laws of
such jurisdiction.