<PAGE>
EXHIBIT 4.1


                          REGISTRATION RIGHTS AGREEMENT


         THIS REGISTRATION RIGHTS AGREEMENT (this "Agreement") is made as of
September 13, 2001 by and among Exten Industries, Inc., a Delaware corporation
(the "Company"), on the one hand, and the Estate of Hugo O. Jauregui (the
"Estate") and the Multi-Cell Associates, Inc. Irrevocable Trust (the "Trust"),
on the other hand.

                                 R E C I T A L S
                                 ---------------

         WHEREAS, pursuant to that certain Stock Purchase Agreement of even date
herewith (the "Stock Purchase Agreement") by and among the Company, Multi-Cell
Associates, Inc., the Trust and the Estate (all capitalized terms not defined
herein as defined therein), the Company is issuing to the Estate and Trust
8,725,000 shares and 3,358,334 shares, respectively, of its common stock, $0.01
par value per share (the "Registrable Securities").

          NOW THEREFORE, in consideration of the foregoing, the parties agree as
follows:

         1. DEFINITIONS.

                  1.1 CERTAIN DEFINITIONS. As used in this Agreement, the
following terms shall have the following respective meanings:

                  "AFFILIATE" of any person or entity shall mean any other
person or entity which, directly or indirectly, controls, is controlled by or is
under common control with such person or entity.

                  "COMMISSION" shall mean the Securities and Exchange Commission
of the United States or any other U.S. federal agency at the time administering
the Securities Act.

                  "HOLDER(S)" shall mean each of the Estate and Trust and their
respective transferees as permitted by SECTION 1.8 and SECTION 2.3 holding
Registrable Securities.

                  "OTHER HOLDERS" shall mean holders of Company securities,
other than Holders, proposing to distribute their securities pursuant to a
registration referred to in this Agreement.

                  "REGISTRABLE SECURITIES" means the shares of the Company's
common stock, $0.01 par value per share, issued to the Holders pursuant to the
Stock Purchase Agreement, and any additional shares of the Company's common
stock issued to the Holders as a stock dividend or as the result of a stock
split with respect to such Registrable Securities.

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                  The terms "REGISTER," "REGISTERED" and "REGISTRATION" refer to
a registration effected by preparing and filing a registration statement in
compliance with the Securities Act, and the declaration or ordering of the
effectiveness of such registration statement.

                  "REGISTRATION EXPENSES" shall mean all expenses, excluding
Selling Expenses (as defined below) except as otherwise stated below, incurred
by the Company in complying with SECTION 1.2 hereof, including, without
limitation, all registration, qualification and filing fees, printing expenses,
escrow fees, fees and disbursements of counsel for the Company blue sky fees and
expenses and the expense of any special audits incident to or required by any
such registration, as well as the reasonable fees and disbursements of one
counsel for the Holders selected by the Holders.

                  "SECURITIES ACT" shall mean the Securities Act of 1933, as
amended, and the rules and regulations of the Commission thereunder, or any
similar United States federal statute.

                  "SELLING EXPENSES" shall mean all underwriting discounts,
selling commissions and stock transfer taxes applicable to the securities
registered by Holders. Such expenses shall be borne by Holders.

                  "SELLING HOLDERS" shall mean each Holder who holds Registrable
Securities included in a registration statement under the Securities Act
pursuant to this Agreement.

                  1.2 REGISTRATION RIGHTS.

                           (a) The Company agrees to file a registration
statement with the Commission within ten (10) months of the date of this
Agreement to register the resale by the Holders of all of the Registrable
Securities and to use its best efforts to cause such registration statement (and
any related qualification under blue sky laws or other compliance) to be
declared effective by the Commission on or before the first anniversary of the
date hereof. The Company agrees to give the Holders at least fifteen (15) days
notice prior to its intended filing of the registration statement.

                           (b) If, prior to the occurrence of the events
described in Section 1.2(a) above, the Company shall determine to register any
of its securities on a form that would permit the registration of the
Registrable Securities, the Company shall promptly give to each Holder written
notice of such registration (a "Piggyback Registration"), and include in such
registration (and any related qualification under blue sky laws or other
compliance), all the Registrable Securities specified in a written request or
requests, made by any Holder or Holders within fifteen (15) days after receipt
of such written notice from the Company.

                  1.3 EXPENSES OF REGISTRATION.

                           (a) REGISTRATION EXPENSES. The Company shall bear all
Registration Expenses incurred in connection with registrations pursuant to
SECTION 1.2.

                           (b) SELLING EXPENSES. Unless otherwise stated, all
Selling Expenses relating to securities registered on behalf of the Holders
shall be borne by such participating Holders.

                  1.4 REGISTRATION AND QUALIFICATION. If and whenever the
Company is required to use its best efforts to effect the registration of any
Registrable Securities under the Securities Act pursuant to this Agreement, the
Company will as promptly as is practicable:

                           (a) prepare and file with the Commission and use its
best efforts to cause to become effective, a registration statement under the
Securities Act relating to the Registrable Securities to be offered on such form
as the Company determines and for which the Company then qualifies;

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                           (b) prepare and file with the Commission such
amendments (including post-effective amendments) and supplements to such
registration statement and the prospectus used in connection therewith as may be
necessary to keep such registration statement effective and to comply with the
provisions of the Securities Act with respect to the disposition of all
Registrable Securities until the earlier of such time as all of such Registrable
Securities have been disposed of in accordance with the intended methods of
disposition set forth in such registration statement or the expiration of two
hundred seventy (270) days after the first anniversary of the Closing Date of
the Stock Purchase Agreement;

                           (c) furnish to the Selling Holders such number of
conformed copies of such registration statement and of each such amendment and
supplement thereto (in each case including all exhibits), such number of copies
of the prospectus included in such registration statement (including each
preliminary prospectus and any summary prospectus), in conformity with the
requirements of the Securities Act, such documents incorporated by reference in
such registration statement or prospectus, and such other documents, as the
Selling Holders or such underwriter may reasonably request;

                           (d) make every reasonable effort to obtain the
withdrawal of any order suspending the effectiveness of such registration
statement as early as possible;

                           (e) if requested by a Holder, (i) furnish to each
Selling Holder an opinion of counsel for the Company addressed to each Selling
Holder and dated the date of the closing under the underwriting agreement (if
any) (or if such offering is not underwritten, dated the effective date of the
registration statement), and (ii) use its best efforts to furnish to each
Selling Holder a "comfort" or "special procedures" letter addressed to each
Selling Holder and signed by the independent public accountants who have audited
the Company's financial statements included in such registration statement, in
each such case covering substantially the same matters with respect to such
registration statement (and the prospectus included therein) as are customarily
covered in opinions of issuer's counsel and in accountants' letters delivered to
underwriters in underwritten public offerings of securities and such other
matters as the Selling Holders may reasonably request and, in the case of such
accountants' letter, with respect to events subsequent to the date of such
financial statements;

                           (f) immediately notify the Selling Holders in writing
(i) at any time when a prospectus relating to a registration hereunder is
required to be delivered under the Securities Act of the happening of any event
as a result of which the prospectus included in such registration statement, as
then in effect, includes an untrue statement of a material fact or omits to
state any material fact required to be stated therein or necessary to make the
statements therein, in light of the circumstances under which they were made,
not misleading, and (ii) of any request by the Commission or any other
regulatory body or other body having jurisdiction for any amendment of or
supplement to any registration statement or other document relating to such
offering, and in either such case (i) or (ii) at the request of a Selling Holder
prepare and furnish to such Selling Holders a reasonable number of copies of a
supplement to or an amendment of such prospectus as may be necessary so that, as
thereafter delivered to the purchasers of such Registrable Securities, such
prospectus shall not include an untrue statement of a material fact or omit to
state a material fact required to be stated therein or necessary to make the
statements therein, in light of the circumstances under which they are made, not
misleading;

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                           (g) use its best efforts to list all such Registrable
Securities covered by such registration statement on each securities exchange
and inter-dealer quotation system on which a class of common equity securities
of the Company is then listed, and to pay all fees and expenses in connection
therewith; and

                           (h) upon the transfer of shares by a Selling Holder
in connection with a registration hereunder, furnish unlegended certificates
representing ownership of the Registrable Securities being sought in such
denominations as shall be requested by the Selling Holders or the underwriters.

                  1.5 INDEMNIFICATION.

                           (a) BY COMPANY. The Company will indemnify each
Holder, each of its officers and directors and partners, and each person
controlling such Holder within the meaning of Section 15 of the Securities Act,
with respect to which registration, qualification or compliance has been
effected pursuant to this Agreement, and each underwriter, if any, and each
person who controls any underwriter within the meaning of Section 15 of the
Securities Act, against all expenses, claims, losses, damages or liabilities (or
actions in respect thereof), including any of the foregoing incurred in
settlement of any litigation, commenced or threatened, arising out of or based
on any untrue statement (or alleged untrue statement) of a material fact
contained in any registration statement, prospectus, offering circular or other
document, or any amendment or supplement thereto, incident to any such
registration, qualification or compliance, or based on any omission (or alleged
omission) to state therein a material fact required to be stated therein or
necessary to make the statements therein, in light of the circumstances in which
they were made, not misleading, or any violation by the Company of the
Securities Act or any rule or regulation promulgated under the Securities Act
applicable to the Company in connection with any such registration,
qualification or compliance, and the Company will reimburse each Holder, each of
its officers, directors and partners, each person controlling such Holder, each
such underwriter and each person who controls any such underwriter, for any
legal and any other expenses reasonably incurred, as incurred in connection with
investigating, preparing or defending any such claim, loss, damage, liability or
action, provided that the Company will not be liable in any such case to the
extent that any such claim, loss, damage, liability or expense arises out of or
is based on any untrue statement or omission or alleged untrue statement or
omission, made in reliance upon and in conformity with written information
furnished to the Company by an instrument duly executed by such Holder,
controlling person or underwriter and stated to be specifically for use therein.
If the Holders are represented by counsel other than counsel for the Company,
the Company will not be obligated under this SECTION 1.5(A) to reimburse legal
fees and expenses of more than one separate counsel for the Holders.

                           (b) BY HOLDERS. Each Selling Holder, severally and
not jointly, will indemnify the Company, each of its directors and officers,
each underwriter, if any, of the Company's securities covered by such a
registration statement, each person who controls the Company or such underwriter
within the meaning of Section 15 of the Securities Act, and each other Selling

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Holder, against all claims, losses, damages and liabilities (or actions in
respect thereof) arising out of or based on any untrue statement (or alleged
untrue statement) of a material fact contained in any such registration
statement, prospectus, offering circular or other document, or any omission (or
alleged omission) to state therein a material fact required to be stated therein
or necessary to make the statements therein not misleading, and will reimburse
the Company, such Selling Holders, such directors, officers, underwriters or
control persons for any legal or any other expenses reasonably incurred in
connection with investigating or defending any such claim, loss, damage,
liability or action, in each case to the extent, but only to the extent, that
such untrue statement (or alleged untrue statement) or omission (or alleged
omission) is made in such registration statement, prospectus, offering circular
or other document in reliance upon and in conformity with written information
furnished to the Company by an instrument duly executed by such Selling Holder
and stated to be specifically for use therein. Notwithstanding the foregoing,
the liability of each Selling Holder under this subsection (b) shall be limited
in an amount equal to the net proceeds from the shares sold by such Selling
Holder.

                           (c) PROCEDURE FOR INDEMNIFICATION. Each party
indemnified under paragraph (a) or (b) of this SECTION 1.5 (the "Indemnified
Party") shall, promptly after receipt of notice of any claim or the commencement
of any action against such Indemnified Party in respect of which indemnity may
be sought, notify the party required to provide indemnification (the
"Indemnifying Party") in writing of the claim or the commencement thereof;
provided that the failure of the Indemnified Party to notify the Indemnifying
Party shall not relieve the Indemnifying Party from any liability which it may
have to an Indemnified Party on account of the indemnity agreement contained in
paragraph (a) or (b) of this SECTION 1.5, unless the Indemnifying Party was
materially prejudiced by such failure, and in no event shall relieve the
Indemnifying Party from any other liability which it may have to such
Indemnified Party. If any such claim or action shall be brought against an
Indemnified Party, it shall notify the Indemnifying Party thereof and the
Indemnifying Party shall be entitled to participate therein, and, to the extent
that it wishes, jointly with any other similarly notified indemnifying party, to
assume the defense thereof with counsel reasonably satisfactory to the
Indemnified Party. If any Indemnified Party employs such separate counsel it
will not enter into any settlement agreement, which is not approved by the
Indemnifying Party, such approval not to be unreasonably withheld. If the
Indemnifying Party so assumes the defense thereof, it may not agree to any
settlement of any such claim or action as the result of which any remedy or
relief, other than monetary damages for which the Indemnifying Party shall be
responsible hereunder, shall be applied to or against the Indemnified Party,
without the prior written consent of the Indemnified Party, which shall not be
unreasonably withheld. In any action hereunder as to which the Indemnifying
Party has assumed the defense thereof with counsel reasonably satisfactory to
the Indemnified Party, the Indemnified Party shall continue to be entitled to
participate in the defense thereof, with counsel of its own choice. In such
case, the Indemnifying Party shall continue to be obligated hereunder to
reimburse the Indemnified Party for the costs thereof.

                           (d) CONTRIBUTION. If the indemnification provided for
in this SECTION 1.5 shall for any reason be unavailable to an Indemnified Party
in respect of any loss, claim, damage or liability, or any action in respect
thereof, referred to therein, then each Indemnifying Party shall, in lieu of
indemnifying such Indemnified Party, contribute to the amount paid or payable by
such Indemnified Party as a result of such loss, claim, damage or liability, or
action in respect thereof, in such proportion as shall be appropriate to reflect

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the relative fault of the Indemnifying Party on the one hand and the Indemnified
Party on the other with respect to the statements or omissions which resulted in
such loss, claim, damage or liability, or action in respect thereof, as well as
any other relevant equitable considerations. The relative fault shall be
determined by reference to whether the untrue or alleged untrue statement of a
material fact or omission or alleged omission to state a material fact relates
to information supplied specifically for use in any registration statement,
prospectus, offering circular or other similar document by the Indemnifying
Party on the one hand or the Indemnified Party on the other, the intent of the
parties and their relative knowledge, access to information and opportunity to
correct or prevent such statement or omission (including by use of an amended
prospectus on file with the Commission), but not by reference to any Indemnified
Party's stock ownership in the Company. In no event, however, shall a Holder of
Registrable Securities be required to contribute in excess of the amount of the
net proceeds received by such Holder in connection with the sale of Registrable
Securities in the offering which is the subject of such loss, claim, damage or
liability. The amount paid or payable by an Indemnified Party as a result of the
loss, claim, damage or liability, or action in respect thereof, referred to
above in this paragraph shall be deemed to include, for purposes of this
paragraph, any legal or other expenses reasonably incurred by such Indemnified
Party in connection with investigating or defending any such action or claim. No
person guilty of fraudulent misrepresentation (within the meaning of Section
12(f) of the Securities Act) shall be entitled to contribution from any person
who was not guilty of such fraudulent misrepresentation.

                  1.6 INFORMATION BY HOLDER. Holders including any Registrable
Securities in any registration shall furnish to the Company such information
regarding such Holders as shall be necessary to enable the Company to comply
with the provisions hereof in connection with any registration, qualification or
compliance referred to in this Agreement.

                  1.7 RULE 144 REPORTING. With a view to making available the
benefits of certain rules and regulations of the Commission which may at any
time permit the sale of the Registrable Securities to the public without
registration, after such time as a public market exists for the Common Stock of
the Company (but subject to the restriction set forth in Section 2.2), the
Company agrees to use its best efforts to:

                           (a) Make and keep public information available, as
those terms are understood and defined in Rule 144 under the Securities Act, at
all times after the effective date that the Company becomes subject to the
reporting requirements of the Securities Act or the Securities Exchange Act of
1934, as amended (the "Exchange Act");

                           (b) File with the Commission in a timely manner all
reports and other documents required of the Company under the Securities Act and
the Exchange Act (at any time after it has become subject to such reporting
requirements); and

                           (c) Furnish to any Holder forthwith upon request a
written statement by the Company as to its compliance with the reporting
requirements of Rule 144, and of the Securities Act and the Exchange Act, a copy
of the most recent annual or quarterly report of the Company, and such other
reports and documents of the Company and other information in the possession of
or reasonably obtainable by the Company as such Holder may reasonably request in
availing itself of any rule or regulation of the Commission allowing such Holder
to sell any such securities without registration.

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                  1.8 TRANSFER OF REGISTRATION RIGHTS. The rights to cause the
Company to register securities granted Holders under SECTION 1.2 may be assigned
in connection with any transfer or assignment by a Holder of Registrable
Securities provided that: (a) such transfer may otherwise be effected in
accordance with applicable securities laws; (b) such transfer is effected in
compliance with the restrictions on transfer contained in this Agreement and in
any other agreement between the Company and the Holder; and (c) such assignee or
transferee agrees in writing to be bound by the terms of this Agreement and
assumes all of the obligations of the transferring Holder hereunder.

         2. MISCELLANEOUS.

                  2.1 WAIVERS AND AMENDMENTS. With the written consent of the
Company and a majority in interest of the Holders, the obligations of the
Company and the rights of the Holders under this Agreement may be amended or
modified; provided, however that no amendment or waiver shall be detrimental to
one or more Holders in any manner different than the manner in which the others
are affected without the written consent of each Holder affected in a more
detrimental manner than any other. It is acknowledged that the granting by the
Company of additional demand or other registration rights to bona fide third
party investors in the Company shall not constitute an amendment or modification
for this purpose. Neither this Agreement nor any provisions hereof may be
changed, waived, discharged or terminated orally, but only by a signed statement
in writing. Any amendment effected in accordance with this paragraph shall be
binding upon the Holders, each future holder of any Registrable Securities and
the Company.

                  2.2 No Sale of Registrable Securities. The Holders agree not
to sell or otherwise transfer or dispose of any Registrable Securities for a
period of one year after the date of this Agreement. The Company may impose
stop-transfer instructions with respect to the Registrable Securities subject to
the foregoing restriction until the end of said period.

                  2.3 ASSIGNMENT OF RIGHTS. The rights to which the Holders are
entitled hereunder are assignable in connection with any transfer of Registrable
Securities, to any transferee or assignee of Registrable Securities who is a
family member of such Holder, or to a trust created for the benefit of such
Holder or members of such Holder's family and, in the case of the Trust, to the
beneficiaries of the Trust.

                  2.4 NOTICES. All notices and other communications required or
permitted hereunder shall be in writing (or in the form of a telecopy (confirmed
in writing) to be given only during the recipient's normal business hours unless
arrangements have otherwise been made to receive such notice by telecopy outside
of normal business hours) and shall be mailed by registered or certified mail,
postage prepaid, or otherwise delivered by hand, messenger, or telecopy (as
provided above) addressed (a) if to any Holder, at the address for such Holder
set forth on EXHIBIT A hereto or at such other address as such Holder shall have
furnished to the Company in writing, or (b) if to any other holder of
Registrable Securities, at such address as such holder shall have furnished the
Company in writing, or (c) if to the Company, to the address set forth in the
Stock Purchase Agreement, addressed to the attention of the Chief Executive
Officer (or at such other address as the Company shall have furnished in writing
to the Holder).

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                  2.5 DESCRIPTIVE HEADINGS. The descriptive headings herein have
been inserted for convenience only and shall not be deemed to limit or otherwise
affect the construction of any provisions hereof.

                  2.6 GOVERNING LAW. This Agreement shall be governed by and
interpreted under the laws of the State of Delaware as applied to agreements
among Delaware residents, made and to be performed entirely within the State of
Delaware.

                  2.7 COUNTERPARTS. This Agreement may be executed in one or
more counterparts, each of which shall for all purposes be deemed to be an
original and all of which shall constitute the same instrument, but only one of
which need be produced.

                  2.8 FACSIMILE SIGNATURES. Any signature page delivered by a
fax machine or telecopy machine shall be binding to the same extent as an
original signature page, with regard to any agreement subject to the terms
hereof or any amendment thereto. Any party who delivers such a signature page
agrees to later deliver an original counterpart to any party which requires it.

                  2.9 EXPENSES. If any action at law or in equity is necessary
to enforce or interpret the terms of this Agreement, the prevailing party shall
be entitled to reasonable attorney's fees, costs and necessary disbursements in
addition to any other relief to which such party may be entitled.

                  2.10 SUCCESSORS AND ASSIGNS. Except as otherwise expressly
provided in this Agreement, this Agreement shall benefit and bind the
successors, assigns, heirs, executors and administrators of the parties to this
Agreement.

                  2.11 ENTIRE AGREEMENT. This Agreement constitutes the full and
entire understanding and agreement between the parties with regard to the
subject matter of this Agreement.

                  2.12 SEPARABILITY; SEVERABILITY. Unless expressly provided in
this Agreement, the rights of each Holder under this Agreement are several
rights, not rights jointly held with any other Holder. Any invalidity,
illegality or limitation on the enforceability of this Agreement with respect to
any Holder shall not affect the validity, legality or enforceability of this
Agreement with respect to the other Holders. If any provision of this Agreement
is judicially determined to be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not be affected or
impaired.

                  2.13 STOCK SPLITS. All references to numbers of shares in this
Agreement shall be appropriately adjusted to reflect any stock dividend, split,
combination or other recapitalization of shares by the Company occurring after
the date of this Agreement.

                  2.14 AGGREGATION OF STOCK. All shares of the Registrable
Securities held or acquired by affiliated entities or persons shall be
aggregated together for the purpose of determining the availability of any
rights under this Agreement.

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                  2.15 DELAYS OR OMISSIONS; REMEDIES CUMULATIVE. No delay or
omission to exercise any right, power or remedy accruing to any party, upon any
breach or default under this Agreement, shall impair any such right, power or
remedy of such party or be construed to be a waiver of any such breach or
default, or an acquiescence therein, or of or in any similar breach or default
thereafter occurring; nor shall any waiver of any single breach or default be
deemed a waiver of any other breach or default theretofore or thereafter
occurring. All of a party's remedies, either under this Agreement, or by law or
otherwise afforded to such party, shall be cumulative and not alternative.

                  2.16 ENFORCEMENT. If the Company shall default in any of its
obligations under this Agreement or if any representation or warranty made by or
on behalf of the Company in this Agreement or in any certificate, report or
other instrument delivered under or pursuant to any term hereof shall be untrue
or misleading as of the date of this Agreement or as of the date it was made,
furnished or delivered, the Holders may proceed to protect and enforce their
rights by suit in equity or action at law, whether for the specific performance
of any term contained in this Agreement, injunction against the breach of any
such term or in furtherance of the exercise of any power granted in this
Agreement, or to enforce any other legal or equitable right of the Holders or to
take any one of more of such actions. In the event the Holders bring an action
against another such party, the prevailing party in such dispute shall be
entitled to recover from the losing party all fees, costs and expenses enforcing
any right of such prevailing party under or with respect to this Agreement,
including such reasonable fees and expenses of attorneys and accountants, which
shall include all fees, costs and expenses of appeals.

                         [Signatures On Following Page]

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          IN WITNESS WHEREOF, the parties have executed this Registration Rights
Agreement as of the date first written above.

                                 COMPANY:

                                 Exten Industries, Inc.


                                 By: /S/ W.G. NEWMIN
                                    --------------------------------------------
                                 Name:    W.G. NEWMIN
                                      ------------------------------------------
                                 Title:   CHAIRMAN & CEO
                                       -----------------------------------------



                                 HOLDERS:

                                 The Estate of Hugo O. Jauregui

                                 By: /S/ CANDACE L. DYER
                                    --------------------------------------------
                                          Candace L. Dyer, Co-Executor

                                 By: /S/ TIMOTHY VAN JOHNSON
                                    --------------------------------------------
                                          Timothy Van Johnson, Co-Executor



                                 Multi-Cell Associates, Inc. Irrevocable Trust

                                 By: /S/ CANDACE L. DYER
                                    --------------------------------------------
                                 Name: CANDACE L. DYER
                                       -----------------------------------------
                                 Title: TRUSTEE
                                       -----------------------------------------

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