This is a A-RC50M Metric Roller Chain PN: RC50MMain Description As Following : A-RC50M Metric Roller Chain P.N: RC50M B1: 3/8" / 9.65 MMD1: 10.16 MMD2: 5.08 MMDIN: 10 B - 1Length: 16'P: 5/8" / 15.875 MM Crossed From: 10B MISCELLANEOUS Found in Section & Models : Chains/ Sprockets/ Pulleys/ Hubs > Metric Roller Chains and Attachment Links, (Miscellaneous) (UNDEFINED): SEVERAL Associated Items : A-CCL1112, A-CL50M, A-OL50M, A-5A1 Also This is An Aftermarket Product And : DIN: 10 B - 1 Length: 16' Pin Diameter: 5.08 MM Pitch: 5/8" / 15.875 MM Width: 3/8" / 9.65 MM