The BT-4 Players Parts Kit has all of the spare replacement parts you’ll need for your BT-4 marker.Players Parts Kit Includes:•1-Ball Detent Assembly•1-Receiver Screw•1-Shock Absorber O-Ring•1-Rear Bolt O-Ring (Exterior Valve O-Ring)•1-Linkage Arm•2-Short Receiver Screws•1-Long Receiver Bolt•1-Drive Spring•2-Shell Nuts•1-Sear Spring•1-Trigger Return Spring•2-Valve Screws•1-Safety O-Ring•1 set of Grip Frame Screws