This listing is for a 5/8" UNF Slotted Castle Nut for Trailer Suspension Hubs / Bearings. Fits any trailer with a 5/8" UNF bearing thrust nut. Slots in the nut allow a split pin to be used to prevent the nut turning. Self-colour. Before fitting it is essential that you check the new part is identical to the original part. If in doubt consult a professional.