Document:

<PAGE>

                                                                     Exhibit 4.4

                                   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 Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees:

     We have been appointed by Aroc Inc., a Delaware corporation (the
"Company"), to act as Depositary in connection with the Company's offer 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 Company's Offer to Purchase, dated May 14, 2001 (the "Offer to
Purchase"), and the related Letters of Transmittal (which, together with the
Offer to Purchase and any amendments or supplements hereto or thereto,
collectively, constitute the "Offer"), enclosed herewith.  Please furnish copies
of the enclosed materials to those of your clients for whose accounts you hold
Shares registered in your name or in the name of your nominee.

     Enclosed for your information and use are copies of the following
documents:

          1.  Offer to Purchase, dated May 14, 2001;

          2.  Letter of Transmittal to be used by holders of Shares in accepting
     the Offer and tendering Shares;

          3.  Notice of Guaranteed Delivery to be used to accept the Offer if
     the Shares and all other required documents are not immediately available
     or cannot be delivered to Registrar and Transfer Company (the "Depositary")
     by the Expiration Date;

          4.  A letter to stockholders of the Company from the Company;

          5.  A letter that may be sent to your clients for whose accounts you
     hold Shares registered in your name or in the name of your nominee, with
     space provided for obtaining such clients' instructions with regard to the
     Offer;

          6.  Guidelines for Certification of Taxpayer ID Number on Substitute
     Form W-9; and

          7.  Return envelope addressed to the Depositary.
<PAGE>

     WE URGE YOU TO CONTACT YOUR CLIENTS AS PROMPTLY AS POSSIBLE.  PLEASE NOTE
THAT THE OFFER AND WITHDRAWAL RIGHTS EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY
TIME, ON JUNE 12, 2001, UNLESS THE OFFER IS EXTENDED.

     In all cases, payment for Shares accepted for payment pursuant to the Offer
will be made only after timely receipt by the Depositary of certificates
evidencing such Shares, a Letter of Transmittal (or facsimile thereof) properly
completed and duly executed and any other required documents.

     If holders of Shares wish to tender, but cannot deliver their certificates
or other required documents prior to the expiration of the Offer, a tender of
Shares may be effected by following the guaranteed delivery procedure described
under "The Tender Offer-Procedures for Accepting the Offer and Tendering Shares"
in the Offer to Purchase.

     The Company will not pay any fees or commissions to any broker, dealer or
other person (other than the undersigned as described in the Offer) in
connection with the solicitation of tenders of shares pursuant to the Offer.
However, the Company will reimburse you for customary mailing and handling
expenses incurred by you in forwarding any of the enclosed materials to your
clients. The Company will pay or cause to be paid any stock transfer taxes
payable with respect to the transfer of Shares to it, except as otherwise
provided in Instruction 6 of the Letter of Transmittal.

     Any inquiries you may have with respect to the Offer and any requests for
additional copies of the enclosed material should be addressed to the
undersigned at the address and telephone number set forth on the back cover page
of the Offer to Purchase.

                                    Very truly yours,

                                    REGISTRAR AND TRANSFER COMPANY

     NOTHING CONTAINED HEREIN OR IN THE ENCLOSED DOCUMENTS SHALL RENDER YOU, OR
ANY OTHER PERSON, THE AGENT OF THE COMPANY, THE DEPOSITARY, OR ANY AFFILIATE OF
ANY OF THEM, OR AUTHORIZE OR ANY OTHER PERSON TO USE ANY DOCUMENT OR TO MAKE ANY
STATEMENT ON BEHALF OF ANY OF THEM IN CONNECTION WITH THE OFFER OTHER THAN THE
ENCLOSED DOCUMENT AND THE STATEMENTS CONTAINED THEREIN.<PAGE>

                                                                     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
<PAGE>

          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.<PAGE>

                                                                     Exhibit 4.6

                                                                     [LOGO]
                                   AROC INC.
                       4200 East Shelly Drive, Suite 1000
                             Tulsa, Oklahoma 74135

                                  May 14, 2001

Dear Stockholders:

     We are offering to purchase any and all of the outstanding shares of our
common stock (the "Shares") from existing stockholders for a purchase price of
$0.06 per share, net to the seller in cash (the "Offer"). THIS OFFER IS NOT
CONDITIONED UPON ANY MINIMUM NUMBER OF SHARES BEING TENDERED. Although the offer
is being made to all holders of the shares, MPAC Energy, LLC, our largest
stockholder, has advised us that it does not intend to tender any Shares
pursuant to this Offer.

     The Board of Directors has not determined whether AROC will continue as a
public company.  MPAC has advised us that, if the Offer is consummated, they
will consider a second-step transaction in which the remaining public
stockholders would receive cash for their shares.  As a result, MPAC would own
100% of AROC and we would no longer be publicly owned.  The consideration
received in any second-step transaction could be higher, the same or lower than
the purchase price in the Offer, although in all likelihood the consideration
will be less than the purchase price in the Offer.

     If a second-step transaction does not occur, it is nevertheless likely that
the Shares will no longer be quoted on the Pink Sheets Electronic Quotation
Service,  and that AROC will no longer file reports with the SEC.  Under these
circumstances, we would become a private company with all remaining
stockholders, other than MPAC, holding a minority equity position.

     THE PUBLIC MARKET FOR THE SHARES IS VIRTUALLY NONEXISTENT AND WE BELIEVE IT
WILL CONTINUE TO BE CHARACTERIZED BY LOW PRICES AND LOW TRADING VOLUMES.  THIS
OFFER PROVIDES THE STOCKHOLDERS WITH AN OPPORTUNITY TO SELL THEIR SHARES AT A
PRICE HIGHER THAN THOSE RECENTLY AVAILABLE IN THE PUBLIC MARKET.

     The Offer is explained in detailed in the enclosed Offer to Purchase and
Letter of Transmittal.  We encourage you to read these materials carefully
before making any decision with respect to the Offer.  The instructions on how
to tender Shares are also explained in detail in the accompanying materials.

     Prior to the date of this letter, the sales price per share for AROC's
common stock, as reported on May 2, 2001 on the Pink Sheets Electronic Quotation
Service was $0.025.  Any stockholder tendering shares directly to the Depositary
will receive the net purchase price in cash and will not generally incur the
usual transaction costs associated with open-market sales.

     A special committee of the board of directors of AROC (the "Special
Committee"), consisting of the independent director of the board, has determined
that a price of $0.06 per share is fair from a financial point of view to
unaffiliated stockholders.  The Special Committee received a fairness opinion
from its financial advisor, Randall & Dewey, Inc., that a price of $0.06 per
share was fair to the unaffiliated stockholders from a financial point of view.
The Special Committee recommends that the unaffiliated stockholders accept the
Offer and tender their shares pursuant to the Offer.

     The Offer will expire at midnight, New York City time, on June 12, 2001,
unless extended by AROC.  If you have any questions or requests for assistance
or for additional copies of the Offer to Purchase, the Letter of Transmittal and
the Notice of Guaranteed Delivery, you may call Registrar and Transfer Company
at (800) 368-5948.

                                    Sincerely,

                                    John A. Keenan
                                    Chairman, President and Chief
                                    Executive Officer

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00025-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00025-of-00352.parquet"}], [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00025-of-00352.parquet"}]]