Enduro Rubber Sealed Deep Groove Ball Bearings: One of the most commonly used bearings, these types are manufactured with rubber seals inserted into the outer raceway and in contact with the inner race providing protection against the ingress of moisture, dust and other foreign matter and serve to retain the pre-filled grease in the bearing. Typically found in cycle wheels and cranks.
Seals can be easily removed for applications that only require 1 seal. Benefits: Prevents moisture and dirt getting into the bearing, lubricated for life
Note: These bearings may feature 'C3' on the box, this is not in reference to internal clearance and is a manufacturer code.