ACB 3645 1125 BO - 1-1/8 BO, Angular Contact Headset Bearing

ACB 3645 1125 BO - 1-1/8 Black Oxide, Angular Contact Headset Bearing Headset Bearing (30.5mm 41.8mm x 6.3mm; 36 x 45 deg) -Angular-contact headset bearing featuring anti-corrosion Black Oxide/Magnetite treated 52100 High-Carbon Chromium alloy races paired with grade 10 Balls. Black Oxide treatment provides an extra level of corrosion resistance and extended worry-free performanceThis size bearing is also known in the bike Industry by these part numbers:IS42ACB30418KMH-P03K The Enduro line of angular-contact headset bearings start with Black Oxide treated Chromium Steel races and then steps up to full 440C stainless steel. The Black Oxide headset bearings are treated in multiple chemical baths to achieve a 3 micron anti corrosive depth. This process also provides a secondary advantage of heat treatment making them tougher. The BO races then go through a secondary "super grind” polishing the rolling surface mirror smooth. Both Stainless and BO bearings are engineered with the largest ba