Martin 50B8 Sprocket #50 (5/8" pitch) roller chain 5/8 inch Bore 8 Teeth
See Pictures-New Old Stock-Box might be rough from shelf ware
Type B stock bore roller chain sprocket designed for use with #50 (5/8" pitch) roller chains. It features a hub extension on one side and is made of high-carbon steel with non-hardened teeth. As a "stock bore" model, it typically comes with a standard 5/8" plain bore that can be custom-machined to fit your specific shaft requirements.