This 440C stainless steel material provides maximum corrosion resistance bearings. Stainless steel is a good alternative in constant wet conditions, or where sweat becomes a problem such as headset bearings. Enduro Bearings uses LLB type seals and CRC Marine Grease in these bearings to additionally water proof against the elements. 440C stainless steel balls and races Bearing I.D. (mm): 30 mm Thickness: 7 mm Bearing O.D. (mm): 42 mm Manufacturer Number: 6806 Material: Steel