Shengzhou Tomorrow Machinery Co.,Ltd manufacture Double Sprockets for Two Single Chains. For example: DS40A15, DS40ATB21H. Material: Steel/Stainless Steel Bore: Stock Bore The sprocket of Mr. Sprocket is a durable, high-quality, precision chain and sprocket made of 1045 steel and stainless steel. This roller Chain Sprocket is manufactured with optimum performance, durability and strict quality control standards. Another thing worth noting about this sprocket is that it is fully compliant with all ANSI standards, ensuring proper contact between the roller chain and the sprocket, preventing premature wear or breakage. Have no keyways or set screws and can be easily machined to custom sizes.usually the sprocket will match with Roller chain single strand 10-FT Box. We can also offer taper bushing sprocket, finished bore sprocket and customized sprocket. we can offer these at very good prices with fast lead times.