Roller Chain Sprocket; 4" Bore; 180-2 Chain; 54 Teeth; 2 Row of Teeth; No Hardened Teeth; 39.98" Outside Diameter; 38.696" Pitch Diameter; C-Hub Both Sides; Finished Bore Mount; No Bushing; 2-1/4" Chain Pitch; ANSI Roller Chain; Keyway; Steel Material