LIFTMASTER Garage Door Openers 41A3261-1 Dual Gear & Sprocket Assembly For DUAL SPROCKET openers ONLY (1 light units). LiftMaster Models 1046, 1056, 1146, 1156, 1246, 1256, 1246R, 1256R. Chamberlain Models 4001, 710 WHC, 711 WHC. Includes all fasteners and installation instructions.