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                                                                    Exhibit 4.20

                       RESTRICTED STOCK PURCHASE AGREEMENT
                                 (JIM WOHLFORD)

          This RESTRICTED STOCK PURCHASE AGREEMENT (this "Agreement") is dated
as of September 24, 2004, by and between CHIEF MANUFACTURING HOLDING CORP., a
Delaware corporation (the "Company"), and JIM WOHLFORD (the "Stockholder").

          WHEREAS, the Company wishes to sell and the Stockholder wishes to buy
certain shares of the Company's Class B Common Stock (as defined in Section 1
hereof) on the terms and subject to the restrictions contained in this
Agreement; and

          NOW, THEREFORE, in consideration of the mutual promises and agreements
set forth herein, the Company and the Stockholder agree as follows:

          1. DEFINITIONS. As used herein, the following terms shall have the
meanings specified below:

          "Act" has the meaning specified in Section 5(a) hereof.

          "Affiliate" has the meaning specified in the Stockholder Agreement.

          "Agreement" has the meaning specified in the introductory paragraph
hereof.

          "Board" means the Board of Directors of the Company.

          "Called Shares" has the meaning specified in Section 3.2(a) hereof.

          "Cause" means anything constituting "Cause" for termination under the
Employment Agreement.

          "Class A Common Stock" means the Company's Class A Voting Common
Stock, $0.001 par value per share.

          "Class B Common Stock" means the Company's Class B Non-Voting Common
Stock, $0.001 par value per share.

          "Class C Common Stock" means the Company's Class C Voting Common
Stock, $0.001 par value per share.

          "Common Equity Value" means, as of any date, the fair market value (as
determined by an Independent Appraiser pursuant to Section 3.3 hereof) of the
entire common stock equity of the Company (without premium for control or
discounts for minority interests, restrictions on transfer or lack of voting
rights or other premiums or discounts that would be applicable if less than all
of the common stock equity is sold in a single transaction), calculated as of
such date, plus the aggregate consideration to be paid to the Company upon the
exercise of all then outstanding and exercisable warrants, options or
convertible securities pursuant to which the Company is then obligated to issue
shares of Common Stock (excluding any options or

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warrants for which the exercise price per share exceeds the Market Value Per
Share of a share of Common Stock as of such date).

          "Common Stock" means the Class A Common Stock, the Class B Common
Stock and the Class C Common Stock, and any capital stock of the Company which
is (a) not preferred as to dividends or assets over any class of stock of the
Company, (b) not subject to redemption, and (c) issued to the holders of Common
Stock upon any reclassification thereof.

          "Company" has the meaning specified in the introductory paragraph
hereof.

          "Delayed Closing Date" has the meaning specified in Section 7.2
hereof.

          "Disability" has the meaning specified in the Employment Agreement.

          "Disposition Event" means (a) (i) the sale of all or substantially all
of the assets of the Company or its Subsidiaries in a single transaction or
series of related transactions whether by liquidation, dissolution, merger,
consolidation or sale or (ii) the sale or other transfer of at least 51% of the
outstanding shares of Common Stock in a single transaction or a series of
related transactions, in either case to any Person who is not an Affiliate of
the Company, or of a stockholder thereof, immediately prior to such transaction
or transactions, or (b) the effective time of any merger, share exchange,
consolidation, or other business combination of the Company if immediately after
such transaction Persons who hold a majority of the outstanding voting
securities entitled to vote generally in the election of directors of the
surviving entity (or the entity owning 100% of such surviving entity) are not
Persons who, immediately prior to such transaction, held the securities of the
Company entitled to vote generally in the election of directors.

          "Disposition Proceeds" means (i) in the case of a merger or any other
stock transaction, (A) the average price per share received by the holders of
Common Stock or by the Company or its Subsidiaries in connection with such
transaction, multiplied by (B) the sum of (x) the total number of shares of
Common Stock then outstanding, plus (y) the total number of shares of Common
Stock issuable upon exercise or conversion of any then outstanding and
exercisable warrants, options or convertible securities pursuant to which the
Company is then obligated to issue shares of Common Stock, or (ii) in the case
of any liquidation or sale of assets (including, without limitation, the sale by
the Company of the capital stock of its Subsidiaries), the Net Worth of the
Common Stock of the Company immediately prior to such liquidation or immediately
after such sale.

          "Eligible Termination" has the meaning specified in Section 3.3(a)
hereof.

          "Employment Agreement" means the Employment and Non-Competition
Agreement, dated as of September 24, 2004, between Chief Manufacturing, Inc., a
Massachusetts corporation, and the Stockholder.

          "Final Vesting Date" has the meaning specified in Section 3.1 hereof.


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          "Good Reason" has the meaning specified in the Employment Agreement.

          "Independent Appraiser" means an independent investment banking firm,
accounting firm or appraiser of nationally recognized standing.

          "Lenders" has the meaning specified in Section 7.1 hereof.

          "Market Value Per Share" means, with respect to any date, for any
share of Common Stock, (i) the Common Equity Value as of such date, divided by
(ii) the sum of (x) the total number of shares of Common Stock then outstanding,
plus (y) the total number of shares of Common Stock issuable upon exercise or
conversion of any outstanding and exercisable warrants, options or convertible
securities pursuant to which the Company is then obligated to issue shares of
Common Stock (excluding any options or warrants for which the exercise price per
share exceeds the Market Value Per Share of a share of Common Stock as of such
date).

          "Net Worth" means, in connection with any liquidation or sale of
assets by the Company, the consolidated net worth of the Common Stock of the
Company and its Subsidiaries, determined in accordance with generally accepted
accounting principles, taking into account (i) the total consideration received
by the Company for such transaction, (ii) the transaction costs incurred in
connection with such transaction and (iii) any liabilities of the Company and
its Subsidiaries whether or not to be discharged in connection with such
transaction (including, without limitation, payment of the liquidation value and
accrued dividends on any Preferred Stock of the Company).

          "Note" has the meaning specified in Section 2(a) hereof.

          "Original Price Per Share" means $3.00 per Share for each share of
Class B Common Stock.

          "Person" an individual, partnership, limited liability company,
corporation, association, trust, joint venture, unincorporated organization, or
any government, governmental department or agency or political subdivision
thereof.

          "Plan" means the Company's 2003 Equity Incentive Plan attached hereto
as Exhibit A.

          "Preferred Stock" means the Series A Preferred Stock and any capital
stock of the Company which is (a) preferred as to dividends or assets over any
other class of stock of the Company, (b) subject to redemption or (c) issued to
the holders of shares of Preferred Stock upon any reclassification thereof.

          "Public Sale" means the Company's initial public offering of Common
Stock.

          "Purchase Price" has the meaning specified in Section 2(a) hereof.

          "Purchased Shares" has the meaning specified in Section 2(a) hereof.


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          "Put Notice" has the meaning specified in Section 3.3(b) hereof.

          "Put Shares" has the meaning specified in Section 3.3(a) hereof.

          "Repurchase Notice" has the meaning specified in Section 3.2(b)
hereof.

          "Senior Debt" means any credit extensions or other obligations
outstanding at the applicable time of reference under working capital, term loan
or acquisition financing arrangements that are extended on a secured basis and
are customarily provided by commercial lenders. For the avoidance of doubt,
"Senior Debt" shall not include any financing arrangements that would
customarily be considered "mezzanine", "sub debt" or similar financing
arrangements.

          "Senior Debt Documents" has the meaning specified in Section 7.1
hereof.

          "Series A Preferred Stock" means the Company's Series A Participating
Preferred Stock, $0.001 par value per share.

          "Shares" means (a) the Purchased Shares purchased by the Stockholder
pursuant to Section 2(a) of this Agreement and (b) all shares of the Company's
capital stock issued with respect to the Purchased Shares by way of dividend or
stock split or in connection with any merger, consolidation, recapitalization or
reorganization affecting the Company's capital stock.

          "Stock Repurchase Agreement" means the Stock Repurchase Agreement,
dated as of September 24, 2004, by and between the Company and the Stockholder.

          "Stockholder" has the meaning specified in the introductory paragraph
hereof.

          "Stockholder Agreement" means the Stockholder Agreement, dated as of
August 29, 2003, among the Company and its stockholders, as amended and in
effect from time to time.

          "Stockholder Appraiser Notice" has the meaning specified in Section
3.4 hereof.

          "Subsidiary" means, with respect to the Company, any corporation, a
majority (by number of votes) of the outstanding shares of any class or classes
of which shall at the time be owned by the Company or by a Subsidiary of the
Company, if the holders of the shares of such class or classes (a) are
ordinarily, in the absence of contingencies, entitled to vote for the election
of a majority of the directors (or persons performing similar functions) of the
issuer thereof, even though the right so to vote has been suspended by the
happening of such a contingency, or (b) are at the time entitled, as such
holders, to vote for the election of a majority of the directors (or persons
performing similar functions) of the issuer thereof, whether or not the right so
to vote exists by reason of the happening of a contingency.

          "Target Amount" means $110,000,000; provided, that if the Company
enters into any extraordinary transaction, such as a business acquisition or
disposition, the Board in the


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exercise of its business judgment may adjust upward or downward the Target
Amount to take into account such extraordinary transaction.

          "Target Disposition Event" means a Disposition Event in which the
Disposition Proceeds equal or exceed the Target Amount.

          "Termination of Employment" means the termination of the Stockholder's
employment with the Company or any of its Subsidiaries for any reason,
including, without limitation, for resignation, death or Disability of the
Stockholder, and whether or not for Cause. For the avoidance of doubt,
expiration of the term of the Employment Agreement shall not constitute a
resignation.

          "Transfer" has the meaning specified in Section 4 hereof.

          "Unvested Shares" has the meaning specified in Section 3.1 hereof.

          "Vested Shares" has the meaning specified in Section 3.1 hereof.

          "Vesting Acceleration Event" has the meaning specified in Section 3.1
hereof.

          2. PURCHASE AND SALE OF SHARES. (a) Subject to (i) the terms and
conditions hereinafter set forth and in reliance on the representations and
warranties contained herein, and (ii) the Company's receipt of any and all
necessary consents, authorizations and approvals of the transactions
contemplated by this Agreement, the Company hereby agrees to issue and sell to
the Stockholder and the Stockholder hereby agrees to purchase from the Company,
on the date hereof 195,993 shares of Class B Common Stock (the "Purchased
Shares"), which will be evidenced by stock certificate number B23. The aggregate
purchase price paid by the Stockholder for the Shares will be $587,979 (the
"Purchase Price"). On the date hereof (A) the full amount of the Purchase Price
will be paid to the Company by delivery of the Stockholder's promissory note to
the Company in the aggregate principal amount of the Purchase Price and in the
form of Exhibit B hereto (the "Note"), (B) the Company shall deliver to the
Stockholder a certificate or certificates representing the Purchased Shares
(each such certificate to bear the legends set forth in Section 6 hereof) and
(C) the Stockholder will deliver to and pledge the Purchased Shares to the
Company pursuant to the terms of the Note, together with stock powers or other
appropriate instruments of assignment thereof duly executed in blank by the
Stockholder.

          (b) The Company represents and warrants that, after giving effect to
the purchase and sale effected hereby and all other agreements to purchase
capital stock and securities of the Company as of the date hereof, (i) the
authorized capital of the Company consists of (A) 36,485 shares of Series A
Preferred Stock, 36,485 shares of which are issued and outstanding on the date
hereof, (B) 30,000,000 shares of Class A Common Stock, no shares of which are
issued and outstanding on the date hereof, (C) 25,000,000 shares of Class B
Common Stock, 13,916,986 shares of which are issued and outstanding on the date
hereof, and (D) 10,000,000 shares of Class C Common Stock, 4,300,001 shares of
which are issued and


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outstanding on the date hereof, (ii) all such outstanding capital stock (other
than the Shares) is owned as set forth on Schedule 1 hereto and is validly
issued and outstanding, fully paid and non-assessable and (iii) there are no
commitments for the purchase or sale of, and no options, warrants or other
rights to subscribe for or purchase, any securities of the Company other than as
set forth on Schedule 1 hereto.

          3. REPURCHASE OF SHARES.

          3.1. VESTING OF SHARES. On and after the date hereof, the terms of any
repurchase of any Shares shall differ depending on whether such Shares are
"Unvested Shares" or "Vested Shares". Initially, 25% of the Shares shall be
considered "Vested Shares" and all other Shares shall be considered "Unvested
Shares". On each anniversary of September 24, 2004 prior to the Termination of
Employment, commencing with September 24, 2005, 25% of the original number of
Shares shall become "Vested Shares", such that all of the Shares shall be Vested
Shares as of and after September 24, 2007 if the Termination of Employment does
not occur prior to such date. If a Target Disposition Event or a Public Sale
occurs prior to a Termination of Employment (the first such event or sale, a
"Vesting Acceleration Event"), (a) 50% of the then Unvested Shares shall become
Vested Shares upon the occurrence of such Vesting Acceleration Event (the
Unvested Shares that become vested upon the occurrence of such Vesting
Acceleration Event shall consist of the Unvested Shares that were scheduled to
vest first chronologically following such Vested Acceleration Event) and (b) the
remaining 50% of the then Unvested Shares shall become Vested Shares on the
earlier of (i) the date that such Unvested Shares are scheduled to vest under
this Agreement and (ii) the first anniversary date of the occurrence of such
Vesting Acceleration Event (such earlier date, the "Final Vesting Date"),
provided that a Termination of Employment has not occurred for Cause or by
resignation on or prior to the Final Vesting Date. Except pursuant to clause (b)
of the immediately preceding sentence, no Shares which have not already become
Vested Shares shall become Vested Shares upon or after the Termination of
Employment for any reason.

          3.2. REPURCHASE RIGHTS OF THE COMPANY.

          (a) Termination of Employment. Upon the Termination of Employment at
any time and for any reason, the Company shall have the right to repurchase from
the Stockholder, and the Stockholder will at the request of the Company sell to
the Company all (but not less than all) of the Shares then owned by the
Stockholder (the "Called Shares") at a purchase price per Share determined
pursuant to paragraphs (i) and (ii) below:

               (i) in the event that such Termination of Employment is a result
          of the Stockholder's resignation (other than for Good Reason) prior to
          the third anniversary of the date hereof, at a purchase price per
          Share equal to the Original Price Per Share plus interest on such
          amount from the date hereof to the date of repurchase at the rate of
          5% per annum; and

               (ii) otherwise, (A) at a purchase price per Vested Share equal to
          the Market Value Per Share and (B) at a purchase price per Unvested


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          Share equal to the Original Price Per Share plus interest on such
          amount from the date hereof to the date of repurchase at the rate of
          5% per annum.

          (b) Repurchase Closing. The Company's repurchase rights under this
Section 3.2 shall be exercisable at any time within ninety (90) days following
the Termination of Employment by written notice to the Stockholder (the
"Repurchase Notice"). The closing of the repurchase of the Called Shares shall
be held (a) not earlier than five (5) days nor later than thirty (30) days after
delivery of the Repurchase Notice if such Termination of Employment is the
result of the Stockholder's resignation (other than for Good Reason) prior to
the third anniversary of the date hereof or (b) otherwise, not earlier than five
(5) days nor later than thirty (30) days after determination of the Common
Equity Value pursuant to Section 3.4 hereof. The Company's repurchase rights
under this Section 3.2 shall lapse if not exercised within the time periods (if
any) specified above in accordance with the provisions hereof, except as
otherwise provided in Section 7 hereof. Amounts due from the Company to the
Stockholder under this Section 3.2 shall be set off in payment of any amounts
payable from the Stockholder to the Company under the Note. Upon delivery by the
Company of the repurchase price for the Called Shares in accordance with Section
8 hereof, all of the Called Shares shall no longer be deemed to be outstanding,
all of the Stockholder's rights with respect to the Called Shares shall
terminate with the exception of the right of the Stockholder to receive the
repurchase price in exchange therefor pursuant to this Section 3.2, and the
Stockholder hereby appoints the Company as his attorney-in-fact to take all
actions necessary and sign all documents required to cancel such Shares on its
books and records.

          3.3. PUT RIGHTS OF THE STOCKHOLDER.

          (a) Termination of Employment. Upon the Termination of Employment at
any time and for any reason, other than by the Company for Cause at any time or
as a result of the voluntary resignation of the Stockholder (other than for Good
Reason) (an "Eligible Termination"), the Stockholder shall have the right to
require the Company to repurchase from the Stockholder, and the Company will, at
the request of the Stockholder, repurchase from the Stockholder, all (but not
less than all) of the Shares then owned by the Stockholder (the "Put Shares") at
a purchase price per Share determined pursuant to paragraphs (i) and (ii) below:

               (i) at a purchase price per Vested Share equal to the Market
          Value Per Share; and

               (ii) at a purchase price per Unvested Share equal to the Original
          Price Per Share plus interest on such amount from the date hereof to
          the date of repurchase at the rate of 5% per annum.

          (b) Put Closing. The Stockholder's put rights under this Section 3.3
shall be exercisable at any time within ninety (90) days following the date of
the Eligible Termination by delivery of written notice (the "Put Notice") to the
Company. Except as provided in Section 7.2 hereof, the closing of the repurchase
of the Put Shares shall, at the option of the Company, be held not earlier than
five (5) days nor later than thirty (30) days after the determination of the


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Common Equity Value pursuant to Section 3.4 hereof. The Stockholder's put rights
under this Section 3.3 shall lapse if not exercised within the time period
specified above and in accordance with the provisions hereof, except as
otherwise provided in Section 7 hereof. Amounts due from the Company to the
Stockholder under this Section 3.3 shall be set off in payment of any amounts
payable from the Stockholder to the Company under the Note. Upon delivery by the
Company of the repurchase price for the Put Shares in accordance with Section 8
hereof, all of the Shares shall no longer be deemed to be outstanding, all of
the Stockholder's rights with respect to the Put Shares shall terminate with the
exception of the right of the Stockholder to receive the repurchase price in
exchange therefor pursuant to this Section 3.3, and the Stockholder hereby
appoints the Company as his attorney-in-fact to take all actions necessary and
sign all documents required to cancel the Put Shares on its books and records.

          3.4. APPRAISAL. Within fifteen (15) days following his receipt of a
Repurchase Notice from the Company in respect of a repurchase of the Shares
pursuant to Section 3.2(a)(ii) hereof, or simultaneously with his delivery of a
Put Notice, as applicable, the Stockholder shall select three (3) Independent
Appraisers that the Stockholder purposes to determine the Common Equity Value
for purposes of this Agreement and shall notify the Company in writing of such
selection (the "Stockholder Appraiser Notice"). The Independent Appraisers
listed in the Stockholder Appraiser Notice shall be identical to the Independent
Appraisers list in any "Stockholder Appraiser Notice" delivered pursuant to the
Stock Repurchase Agreement. The Company shall select one (1) of the Independent
Appraisers listed in the Stockholder Appraiser Notice and use reasonable
commercial efforts to promptly engage, at the cost and expense of the Company,
such Independent Appraiser to determine the Common Equity Value for purposes of
this Agreement. The terms of such engagement shall provide that the Independent
Appraiser shall complete its determination of the Common Equity Value within 45
days of engagement by the Company and that in determining the Common Equity
Value, the Independent Appraiser must take into account consideration of the
assumptions and methodology used by the Company and other investors in
determining the valuation at which the Stockholder purchased the Purchased
Shares. The Company shall not be required to select any Independent Appraiser
from a Stockholder Appraiser Notice unless the Stockholder Appraiser Notice
includes three (3) Independent Appraisers. If the Stockholder has not provided a
Stockholder Appraiser Notice which materially complies with the requirements of
this Section 3.4 within thirty (30) days following the Stockholder's receipt of
the Repurchase Notice or within fifteen (15) days of delivery of the Put Notice,
as applicable, the Board shall in good faith select an Independent Appraiser to
determine the Common Equity Value. Any determination of the Common Equity Value
by an Independent Appraiser pursuant to this Section 3.4 shall be final,
conclusive and binding upon the parties. The Company shall cooperate with the
Independent Appraiser to the extent necessary to facilitate the determination of
the Common Equity Value.

          4. RESTRICTIONS ON TRANSFER. The Stockholder may not sell, assign,
transfer, pledge or otherwise dispose of ("Transfer") any of the Unvested
Shares, either voluntarily or involuntarily or by operation of law, except to
the Company or any of its Subsidiaries. Except as otherwise expressly provided
in the Stockholder Agreement, the Stockholder may not Transfer any of the Vested
Shares, either voluntarily or involuntarily or by operation of law, except to
the Company or any of its Subsidiaries. On and after the time the


                                       -8-

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Company completes a Public Sale, all of the restrictions on Transfer and the
repurchase rights of the Company contained herein (including, without
limitation, the repurchase rights of the Company pursuant to Section 3 hereof),
shall cease to apply to any Shares that constitute Vested Shares at such time
and to any Shares that become Vested Shares after such time pursuant to the
terms hereof. On and after the completion of a Target Disposition Event, all of
the repurchase rights of the Company contained herein (including, without
limitation, the repurchase rights of the Company pursuant to Section 3 hereof),
shall cease to apply to any Shares that constitute Vested Shares at such time
and to any Shares that become Vested Shares after such time pursuant to the
terms hereof. Under no circumstances may the Stockholder Transfer any Shares in
violation of the terms of the Note. Upon any permitted Transfer of the Shares,
the transferee of the Shares shall execute and deliver to the Company an
agreement containing repurchase provisions substantially the same as those
contained herein.

          5. INVESTMENT REPRESENTATIONS. (a) The Stockholder represents that the
Shares are being acquired by him for his own account for investment and not with
a view to the distribution thereof. The Stockholder understands that the Shares
have not been registered under the Securities Act of 1933, as amended (the
"Act"), on the grounds that the offer and sale of the Shares to him are exempt
from the registration requirements of the Act under Section 4(2) thereof as a
transaction not involving any public offering of the Shares. The Stockholder
understands that the Company's reliance on such exemption is predicated in part
on the representations of the Stockholder which are contained herein.

          (b) The Stockholder understands that he must bear the economic risk of
his investment in the Shares for an indefinite period of time because the Shares
have not been registered under the Act and, therefore, cannot be sold unless
they are subsequently registered under the Act or an exemption from such
registration is available. The Stockholder agrees that he will not offer to
Transfer any of the Shares except as expressly permitted by this Agreement and
then only after the Company has received an opinion of its counsel that such
offer or Transfer is not in violation of the registration requirements of the
Act or other applicable law.

          (c) The Stockholder represents that he is an "accredited investor" (as
defined in Rule 501 under the Act) and a resident of the State of Minnesota.

          6. LEGENDS; STOP TRANSFER. (a) Each certificate representing the
Shares shall bear legends in or substantially in the following form:

          "THE SHARES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
          UNDER THE SECURITIES ACT OF 1933, AS AMENDED. NO TRANSFER, SALE OR
          OTHER DISPOSITION OF THESE SHARES MAY BE MADE UNLESS A REGISTRATION
          STATEMENT WITH RESPECT TO THESE SHARES HAS BECOME EFFECTIVE UNDER SAID
          ACT, OR THE COMPANY HAS BEEN FURNISHED WITH AN OPINION OF COUNSEL
          SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.


                                       -9-

<PAGE>

          THE SHARES EVIDENCED BY THIS CERTIFICATE ARE ALSO SUBJECT TO CERTAIN
          REPURCHASE RIGHTS IN FAVOR OF THE COMPANY AND CERTAIN PROVISIONS
          REGARDING RESTRICTIONS UPON TRANSFER CONTAINED IN A RESTRICTED STOCK
          PURCHASE AGREEMENT, DATED AS OF SEPTEMBER 24, 2004, COPIES OF WHICH
          WILL BE FURNISHED BY THE COMPANY TO THE HOLDER OF THE SHARES EVIDENCED
          BY THIS CERTIFICATE UPON WRITTEN REQUEST AND WITHOUT CHARGE."

          (b) In addition, the Company shall make a notation regarding the
restrictions on transfer of the Shares in the stock books of the Company, and
such Shares shall be transferred on the books of the Company only if and when
transferred or sold in compliance with all of the terms and conditions of this
Agreement.

          7. REPURCHASE RESTRICTIONS.

          7.1. CONTRACTUAL RESTRICTIONS ON REPURCHASE. Notwithstanding any
provision to the contrary in Section 3, if the Company is prohibited by the
terms of any of the financing agreements of the Company or any of its
Subsidiaries with their commercial lenders ("Lenders") providing Senior Debt
(such financing agreements being referred to herein as the "Senior Debt
Documents") from making any payments of any portion of the repurchase price for
the Shares in cash, (a) the Company shall be entitled to complete the repurchase
of such Shares by delivering to the Stockholder (or any permitted transferee
thereof) a promissory note for the portion of the repurchase price, payment of
which is prohibited to be made immediately, and (b) the Company will use
reasonable efforts (including using reasonable efforts to obtain the necessary
consents from the Company's and/or its Subsidiaries' Lenders) to pay the
repurchase price as soon as permitted under such Senior Debt Documents or by
waiver thereof following the repurchase. Each such promissory note shall (i)
bear interest at the rate of five percent (5%) per annum for the first year of
such note, seven and one half percent (7.5%) per annum for the second year of
such note and ten percent (10%) per annum for each year of such note thereafter
until paid in full, (ii) provide for the payment of the principal evidenced
thereby in such installments and at such times as are permitted by the Company's
and its Subsidiaries' Lenders, (iii) be subordinated only to Senior Debt of the
Company and its Subsidiaries provided by their Lenders under the Senior Debt
Documents (including all interest, penalties, fees or other charges under the
Senior Debt Documents governing such Senior Debt from time to time) (the "Lender
Indebtedness") on terms satisfactory to such Lenders and (iv) subject to such
payment and subordination provisions, provide for the payment in full of the
principal and unpaid interest evidenced thereby upon the earlier to occur of:
(x) repayment in full of all of the Lender Indebtedness and (y) a Disposition
Event.

          7.2. IMPAIRMENT OF CAPITAL. If, even after giving effect to the
provisions of Section 7.1 hereof, the Company is prohibited by the terms of any
of the Senior Debt Documents from issuing a promissory note for the balance of
the repurchase price as contemplated by Section 7.1 or is prohibited by law from
repurchasing any of the Shares which it is obligated to repurchase hereunder due
to any existing or prospective impairment of its capital, the closing of


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such repurchase shall be delayed until the first date on which the Company is
permitted by the terms of any such Senior Debt Documents to repurchase such
Shares and has sufficient capital to lawfully repurchase such Shares (the
"Delayed Closing Date"). Where practicable, the Company will continue to use all
reasonable efforts to obtain any necessary consents or waivers from the
Company's or its Subsidiaries' Lenders to permit the closing to occur in
accordance with Section 7.1. In the event of any such delay, (i) the Company
will be obligated to pay, on the Delayed Closing Date, interest on the
repurchase price for such Shares (x) at the rate of five percent (5%) per annum
for the first year from the date on which the closing of the repurchase of such
Shares was originally scheduled to occur to the Delayed Closing Date, (y) at a
rate of seven and one half percent (7.5%) per annum for the second year from the
date on which the closing of the repurchase of such Shares was originally
scheduled to occur to the Delayed Closing Date and (z) at a rate of ten percent
(10%) per annum thereafter until the Delayed Closing Date and (ii) the
Stockholder shall remain bound by the restrictions on Transfer contained herein
during such delay; provided, that the Company shall not be required to issue a
promissory note to evidence its payment obligation to the extent such issuance
is prohibited by the terms of such Senior Debt Documents. If the Company issues
to the Stockholder a promissory note in connection with the closing of the
repurchase of the Shares on the Delayed Closing Date, the initial interest rate
for such promissory note will be determined as if such promissory note was
issued on the date interest began accruing on the repurchase price for the
Shares under this Section 7.2.

          8. PAYMENT FOR SHARES. At any closing held to consummate any
repurchase of the Shares hereunder, the Stockholder shall deliver to the Company
the stock certificates representing such Shares, duly endorsed in blank or with
duly executed stock powers attached, and the Company shall (i) offset the
repurchase price for such Shares against any amounts owed by the Stockholder to
the Company under the Note and (ii) make payment to the Stockholder by wire
transfer or other form of immediately available funds of any remaining balance
of the repurchase price or a promissory note as provided in Section 7.1.

          9. ADJUSTMENT OF REPURCHASE PRICE. Upon any stock split, reverse stock
split, recombination of shares or other similar reorganization of the capital
structure of the Company, the repurchase price otherwise payable to the
Stockholder upon the repurchase of any Shares pursuant to Section 3 hereof shall
be proportionally adjusted to reflect such reorganization.

          10. GENERAL.

          10.1. NOTICES. All notices, demands and other communications hereunder
shall be in writing or by written telecommunication, and shall be deemed to have
been duly given if delivered personally or if mailed by certified mail, return
receipt requested, postage prepaid, or if sent by overnight courier, or sent by
written telecommunication, as follows:


                                      -11-

<PAGE>

               If to the Company, to:

                    Chief Manufacturing Holding Corp.
                    c/o Friedman Fleischer & Lowe LLC
                    One Maritine Plaza
                    Suite 1000
                    San Francisco, California 94111
                    Fax No.: (415) 402-2111
                    Attention: Caleb Everett

               With copies sent simultaneously to:

                    Bingham McCutchen LLP
                    399 Park Avenue
                    New York, New York 10022
                    Fax No: (212) 752-5378
                    Attention: Neil W. Townsend, Esq.

               If to the Stockholder, to:

                    Jim Wohlford
                    [Address]

          Any such notice shall be effective (a) if delivered personally, when
received, (b) if sent by overnight courier, when receipted for, (c) if mailed,
three (3) days after being mailed as described above, and (d) if sent by written
telecommunication, when dispatched.

          10.2. EQUITABLE REMEDIES. Each of the parties hereto acknowledges and
agrees that upon any breach of his or its obligations under Sections 3, 4, 7, or
8 hereof (as applicable), the other party will have no adequate remedy at law,
and accordingly will be entitled to specific performance and other appropriate
injunctive and equitable relief.

          10.3. SEVERABILITY. If any provision of this Agreement is or becomes
invalid, illegal or unenforceable in any respect under any law, the validity,
legality and enforceability of the remaining provisions hereof shall not in any
way be affected or impaired.

          10.4. WAIVERS. No delay or omission by either party hereto in
exercising any right, power or privilege hereunder shall impair such right,
power or privilege, nor shall any single or partial exercise of any such right,
power or privilege preclude any further exercise thereof or the exercise of any
other right, power or privilege.

          10.5. COUNTERPARTS. This Agreement may be executed in multiple
counterparts (including by facsimile), each of which shall be deemed an
original, but all of which together shall constitute one and the same
instrument.


                                      -12-

<PAGE>

          10.6. ASSIGNS. This Agreement shall not be assignable or transferable
by the Stockholder without the Company's prior written consent thereto.

          10.7. ENTIRE AGREEMENT. This Agreement contains the entire
understanding of the parties, supersedes all prior agreements and understandings
relating to the subject matter hereof and shall not be amended except by a
written instrument hereafter signed by each of the parties hereto. Nothing in
this Agreement shall be construed as a grant to the Stockholder of any right to
continuing employment with the Company or any Subsidiary or to restrict in any
way the right to terminate the Stockholder's employment at any time.

          10.8. FURTHER ACTIONS. The parties hereto shall, without further
consideration, execute such additional documents and take such other actions as
may be reasonably necessary to carry out the purposes and intent of this
Agreement and to fulfill their respective obligations hereunder.

          10.9. GOVERNING LAW. This Agreement and the obligations of the parties
hereunder shall be deemed to be a contract under seal and shall for all purposes
be governed by and construed in accordance with the internal laws of The
Commonwealth of Massachusetts without reference to principles of conflicts of
law.

          11. SECTION 83(B) ELECTION. The Stockholder and the Company
acknowledge that the Stockholder will make an election, in accordance with
Section 83(b) of the Internal Revenue Code of 1986, as amended. The Stockholder
and the Company agree that the fair market value of the Shares is equal to the
aggregate Original Purchase Price Per Share of the Shares, and shall reflect
such fair market value to the extent required on any Federal, state or local
income tax return or filing. The Stockholder further agrees that he will file a
Section 83(b) election form with the Internal Revenue Service within thirty (30)
days after the date hereof.

          12. INCORPORATION OF PLAN TERMS. The sale of the Shares to the
Stockholder pursuant to this Agreement is subject to all of the applicable terms
of the Plan, including, but not limited to, Section 9 (Settlement of Awards).

      [Remainder of page intentionally left blank; signature page follows]


                                      -13-

<PAGE>

          IN WITNESS WHEREOF, and intending to be legally bound hereby, the
parties hereto have caused this Agreement to be duly executed as of the date and
year first above written.

THE COMPANY:                            CHIEF MANUFACTURING HOLDING CORP.


                                        By: /s/ ILLEGIBLE
                                            ------------------------------------
                                        Title: PRESIDENT

THE STOCKHOLDER:


                                        ----------------------------------------
                                        Jim Wohlford


                                      -14-

<PAGE>

          IN WITNESS WHEREOF, and intending to be legally bound hereby, the
parties hereto have caused this Agreement to be duly executed as of the date and
year first above written.

THE COMPANY:                            CHIEF MANUFACTURING HOLDING CORP.


                                        By:
                                            ------------------------------------
                                        Title: PRESIDENT

THE STOCKHOLDER:


                                        /s/ Jim Wohlford
                                        ----------------------------------------
                                        Jim Wohlford


                                      -14-

<PAGE>
                                                                    Exhibit 4.20


December 3, 2007


Jim Wohlford
[Address]

Mr. Wohlford:

Reference is hereby made to that certain Restricted Stock Purchase Agreement,
dated as of September 24, 2004 (the "Agreement"), by and between Jim Wohlford
and Milestone AV Technologies, Inc. (f/k/a "CSAV Holding Corp.") ("Milestone")
for the purchase of 280,270 shares of Class B Common Stock of Milestone (as
adjusted for stock splits effected by Milestone, the "Class B Shares"). Pursuant
to the Section 4 of the Agreement, the right of Milestone to purchase the Class
B Shares that are vested will expire upon the consummation of an initial public
offering of the common stock of Milestone (an "IPO"). By signing this letter
agreement, you hereby agree that the Agreement is hereby amended to provide that
your put rights set forth in Section 3.3 of the Agreement with respect to all
vested Class B Shares shall also expire upon the consummation of an IPO.

Please indicate your agreement by signing in the space indicated below and
sending a signed copy via facsimile to 212-702-3624.

Sincerely,


MILESTONE AV TECHNOLOGIES, INC.

/s/ Scott Gill
--------------------------------
Scott Gill
Chief Executive Officer


ACCEPTED AND AGREED:

/s/ Jim Wohlford
--------------------------------
Jim Wohlford