This is a A-55CO 55CO Attachment Link PN: 55COMain Description As Following : A-55CO 55CO Attachment Link P.N: 55CO Dim A (1): 1-3/8Dim F (6): 5/8Dim Q (17): .125 Crossed From: 55CPLR , 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): 1-3/8 Dim F (6): 5/8 Dim Q (17): .125