New! BSA & Triumph Unit Singles Mainshaft Ball Bearing. Looking for a High Quality Bearing that you can trust and rely on? Well this is Exactly you need! Don’t Skimp on your Engine! Do it right the First Time! Fits BSA Unit Singles (C15, B40, B44, C25, B25, TR25W Trophy, B25SS, B50, TR5MX & B50MX) from 1965-1973. Also fits various BSA C11 & C12. Norton 18, ES2, Dominator & Commando. Please refer to your parts catalog for proper fitment.O.E.M Part number is 90-0011, LS7, LJ5/8, RLS5 or 70-8151