C3 bearings have an additional internal radial clearance to cope with high speed environments where excess heat is generated. Shielded Type: With metal shields inserted into the outer raceway, these fit in closely to the inner race providing moderate protection against mechanical damage, and against the ingress of moisture, dust and other foreign objects. The shields also retain the pre-filled grease in the bearing. Shields can be easily removed for applications that only require one shield.
