Commercial Door Opener, Manual Chain Hoist, Max. Door Height (Ft.) 16, Max. Door Width (Ft.) 22, Commercial, Industrial, Residential, External Gear Drive, Standards 1-1/4 in Bore, Includes (18) 2-5/16 in Set Screw, #41 Sprocket, 1-1/4 in Key, 1-36 1-1/4 in Tooth, 26 ft Hand Chain, 4 ft #41 Roller Chain, Chain Keeper Bracket