This is a A-51 51 Steel Detachable Chain (10 ft) PN: 51Main Description As Following : A-51 51 Steel Detachable Chain (10 ft) P.N: 51 Dim A (1): 1-3/32Dim B (2): 45/64Dim C (3): 1-5/32 Crosses To: A-B1BPR8ES AUTOLITE , A-LF513 LEDERER , A-LF513J LEDERER , A-LF647 DELUXE , A-LF647J DELUXE , A-LF782 FACET , A-LF782J FACET , Crossed From: 042-T5100 , , 042T5100 , , 2221-23321 JOHN DAY , 51DC , Found in Section & Models : Chains/ Sprockets/ Pulleys/ Hubs > Steel Detachable Chains, (Miscellaneous) (UNDEFINED): SEVERAL Associated Items : New Also This is An Aftermarket Product And : Dim A (1): 1-3/32 Dim B (2): 45/64 Dim C (3): 1-5/32