Roller Chain Sprocket; 1-1/4" Bore; 40 Chain; 20 Teeth; 1 Row of Teeth; Hardened Teeth; 3.457" Outside Diameter; 3.196" Pitch Diameter; B-Hub One Side; Finished Bore Mount; No Bushing; 1/2" Chain Pitch; ANSI Roller Chain; Keyway; Steel Material