Gear and Sprocket Replacement Kit Includes: Gear and sprocket, worm gear, grease, motor shaft bearings, sprocket bearings Compatible with Chamberlain, Sears, Craftsman and LiftMaster 1/3 and 1/2 HP chain drive models Compatible with chain drive Chamberlain Sears Craftsman manufactured operators 1984-current Installation: Step-by-step instructions included, free tech support available. This OEM kit 041c4220a includes all of the 41A2817 Drive / Worm Gear kit, and is easier to install because you do not have to disassemble the output shaft assembly - the spur gear is already mounted on the new output shaft