National Hardware Door Pulley, Series: N280, 0.56 in Bore, 4-1/4 in Outer Diameter, 4 in Sheave Width, 1 Grooves, 0.71 in Groove, Hook Mounting, Steel, Galvanized, Includes: Spring Clevis Hook, Nut and Bolt, Standards: BHMA A138.18, Used On Double Car Doors