Note the variety of sizes to suit different axles
Some US axles - 36mmDia
TMC - 40mm Dia
Dexter - model F22 - 45mm Dia
Hendrickson - model HN S18146-1 - 45mm Dia
BPW - 45mm Dia
KGI - 45mm Dia
ROR TM - 45mm Dia
ROR LM - 63mm Dia
Dexter - model F24 - 70mm Dia
Henrickson - model HP  S18146-3 - 70mm Dia