<PAGE>

                                FOURTH AMENDMENT TO 
                      EXCLUSIVE LICENSE AND ROYALTY AGREEMENT


     THIS FOURTH AMENDMENT ("Amendment") to the Exclusive License and Royalty 
Agreement ("Royalty Agreement") dated as of April 17, 1993, by and between 
LARRY A. RASMUSSON, residing at 1485 - 139th Lane Northwest, Andover, 
Minnesota (hereinafter referred to as "Rasmusson") and OXBORO OUTDOORS, INC., 
a Minnesota corporation having its principal place of business at 13828 
Lincoln Street, Ham Lake, Minnesota  55304 (hereinafter referred to as the 
"Company"), is made effective as of the 1st day of September, 1998.

                                      RECITALS

     WHEREAS, and Rasmusson entered into the Third Amendment to the Royalty 
Agreement effective as of February 25, 1998;

     WHEREAS, the Third Amendment reduced the Royalties payable to Rasmusson 
under the Royalty Agreement for a period of time and caused the Parent of the 
Company to issue on behalf of the Company shares of stock of the Parent to 
Rasmusson in escrow.

     WHEREAS, the Company and Rasmusson desire to rescind the Third Amendment 
to the Royalty Agreement in its entirety and to effect certain other 
amendments to the Royalty Agreement pursuant to the terms and conditions set 
forth herein.

     NOW, THEREFORE, in consideration of the recitals set forth above and in 
further consideration of the terms and conditions set forth below, Rasmusson, 
Company and Parent agree to amend the Agreement as follows:

          1.   RESCISSION OF THIRD AMENDMENT TO EXCLUSIVE LICENSE AND ROYALTY 
     AGREEMENT.  The Third Amendment to the Exclusive License and Royalty 
     Agreement effective the 25th day of February, 1998, is hereby rescinded 
     in its entirety.  The 150,000 shares issued to Rasmusson (Certificate of 
     Common Stock of Oxboro Medical International, Inc. No. __) shall be and 
     are hereby returned to Oxboro Medical International, Inc. duly endorsed 
     by Rasmusson or with an attached Assignment Separate From Certificate.
          
          2.   AMENDMENT TO SUBSECTION 4.1.  Section 4.1 of the Royalty  
     Agreement is hereby amended in its entirety as follows:

               4.1  The Company will pay to Rasmusson Royalties in the amount 
          set forth below on the NET SALES PRICE of all PRODUCTS sold by the 
          Company during the revised term of this Royalty Agreement:
               
                    (a)  The Company will pay Rasmusson Royalties in the 
               amount of eight percent (8%) up to One Million Dollars of NET 
               SALES PRICE of PRODUCTS and nine percent (9%) for all net 

<PAGE>

               sales in excess of One Million Dollars until Royalty advances 
               (currently in the approximate amount of Eighty Thousand and 
               No/100 Dollars ($80,000.00)) are consumed; thereafter 
               Royalties shall be paid pursuant to subparagraph b;
                    
                    (b)  Royalties shall be paid as set forth in the 
               following table on the cumulative NET SALES PRICE of PRODUCTS 
               sold by the Company for each fiscal year:
<TABLE>
<CAPTION>
               --------------------------------------------------------------
                        Cumulative NET SALES              ROYALTY
                          PRICE OF PRODUCTS             PERCENTAGE
               --------------------------------------------------------------
                      <S>                               <C>
                          $0 to $1,000,000                  4%
               --------------------------------------------------------------
                      $1,000,000 to $2,000,000              6%
               --------------------------------------------------------------
                           Over $2,000,000                  8%
               --------------------------------------------------------------
</TABLE>

          3.   AMENDMENT TO SECTION 8.  Section 8 of the Royalty Agreement 
     entitled Duration and Termination is hereby amended in its entirety as 
     follows:
          
               8.   DURATION AND TERMINATION.
                    
                    (a)  This Contract shall terminate at 11:59 p.m. on 
               August 31, 2001.  Upon termination, Rasmusson shall have no 
               further rights with respect to the PRODUCTS or Additional 
               Products being sold at that time or to PRODUCTS and Additional 
               Products which have not previously reverted to Rasmusson.  

                    (b)  Prior thereto, this Contract may be terminated by 
               either party in the event of a breach under or default in the 
               performance of any material provision, term or condition of 
               this Contract and the giving of written notice specifying the 
               alleged breach or default, if the party in breach or default 
               fails to cure the alleged breach or default within thirty (30) 
               days of receipt of notice, or fails to commence actions to 
               cure the breach or default within such thirty (30) days period 
               and thereafter diligently prosecute and pursue such cure to 
               completion.  

                    (c)  In the event of termination of this Contract as a 
               result of a default by the Company, the Company will 
               immediately lose all rights to manufacture, produce and sell 
               the PRODUCTS and the Additional Products, which rights shall 
               immediately revert to Rasmusson; provided, however, that the 
               Company will have the right to sell its inventory of any 
               completed PRODUCTS and Additional Products manufactured or 
               produced as of the date of such termination for a period of 
               ninety (90) days from the date of such termination.  The 
               Company will also immediately lose all rights to use the 
               KNOW-HOW, will cease using the KNOW-HOW in all respects, and 
               will transfer all rights pertaining to the KNOW-


                                       2
<PAGE>

               HOW back to Rasmusson.  The Company will continue to pay 
               Royalties as provided in this Contract based on the NET SALES 
               PRICE of PRODUCTS or Additional Products sold by the Company 
               following the termination of this Contract.  The Company will 
               assign to Rasmusson all patents, trademark registrations, 
               copyrights and similar intellectual property rights, as well 
               as all applications therefore, which relate to or are derived 
               from the PRODUCTS, the Additional Products or the KNOW-HOW; 
               and Rasmusson will have the right to utilize the KNOW-HOW and 
               to manufacture and sell the PRODUCTS and the Additional 
               Products, either on his own account or through such other 
               persons or entities as he may select. 

          4.   ARBITRATION.  Any controversy or dispute arising under the 
     terms of this Agreement shall be determined by arbitration in 
     Minneapolis, Minnesota, according to the then current Rules and 
     Regulations of the American Arbitration Association and the decision of 
     the arbitrator or arbitrators shall be final and binding upon all 
     parties and may be entered as a final judgment in any court of competent 
     jurisdiction.  The costs and arbitrators fees of the prevailing party 
     shall be paid by the non-prevailing party.  

          5.   NOTICES.  All notices required under this Agreement shall be 
     given in writing and shall be sufficiently given if delivered to the 
     addressee in person or, if mailed, by certified mail, return receipt 
     requested, and addressed as follows:
<TABLE>
               <S>                 <C>
               If to Parent:       President
                                   Oxboro Medical International, Inc.
                                   13828 Lincoln Street NE
                                   Ham Lake, Minnesota  55304
     
               If to Company:      Oxboro Outdoors, Inc.
                                   c/o The Board of Directors
                                   Oxboro Medical International, Inc.
                                   13828 Lincoln Street NE
                                   Ham Lake, Minnesota  55304
     
               If to Rasmusson:    Larry A. Rasmusson
                                   1485 - 139th Lane N.W.
                                   Andover, MN  55304
</TABLE>

          Any notice shall be deemed effective (i) when delivered if 
     delivered personally and (ii) five (5) days after deposit in the mail, 
     return receipt requested.
     
     All other terms and conditions of the Royalty Agreement, as amended, 
shall remain unchanged, subject to future amendment by written agreement of 
the parties hereto.


                                       3
<PAGE>

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


COMPANY:                                RASMUSSON:

OXBORO OUTDOORS, INC.


 By:  /s/ Robert S. Garin                  /s/ Larry A. Rasmusson
    -----------------------------        -----------------------------
     Its:  Chairman of the Board         Larry A. Rasmusson
         ------------------------



PARENT:

Consented and Agreed to this 21st day of _______,1998.

OXBORO MEDICAL INTERNATIONAL, INC.


By:  /s/ Robert S. Garin 
    -----------------------------
    Its:  Chairman of the Board  
        -------------------------


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