Apparatus for endoscopic procedures

A surgical stapling apparatus includes a handle assembly, a shaft assembly extending distally from the handle assembly, and an end effector selectively detachable from the shaft assembly. The end effector includes a first jaw member and a second jaw member. The first jaw member supports a lever that is pivotally movable relative to the first jaw member between an extended position and a retracted position. The lever is in contact with a leaf spring to spring bias the lever to the extended position. The second jaw member supports a drive beam that is selectively engagable with the lever to facilitate a pivotal movement of the second jaw member relative to the first jaw member between an unapproximated state and an approximated state.