A surgical instrument for use in connection with a pneumatically powered tool having a firing mechanism operably supported therein that is movable between an unactuated position and an actuated position. In various embodiments, a drive system operably communicates with the pneumatically powered tool...http://www.google.com.hk/patents/US7448525?utm_source=gb-gplus-share專利 US7448525 - Pneumatically powered surgical cutting and fastening instrument with manually operated retraction apparatus
