Check the listing for details. BLACK POWDER CANNON SLAP HAMMER TRIGGER SYSTEM. Condition: New. Listed at 89.99 USD. DESCRIPTION: PLEASE READ!This auction is for the SLAP HAMMER SYSTEM ONLY, not for the cannon or the primers in the photos.This is a SLAP HAMMER TRIGGER SYSTEM. It is super simple to use! This convenient and fun way to shoot off your cannon uses #209 primers ** NOT INCLUDED ** Simply add a primer to the fuse hole, position the hammer back and pull the string to shoot off the cannon. It replaces using cannon fuse. It works time after time. A little modification is needed to accomodate the #209 primer. The already existing fuse hole needs to be slightly enlarged to a diameter of .25" and to a depth of also .25" and the primer will fit snugly. The hammer system itself is affixed to the cannon with one small shallow screw. Simple drilling and tapping is required. Another great product made in the USA by EmpireCannons