These sprockets are use with #40 roller chain as driver or driven sprockets requirments Bore to size sprockets Roller chain sprockets Finish bore sprockets Made In India These are type BS sprocket, also known as a bored-to-size sprocket, includes two setscrews and a keyway, and is suitable for use with the series 40 chain with a 1/2? pitch. This sprocket has been adapted for installation on the shaft without additional components. Made from high carbon steel, it has high strength and durability.