UC213-40 Black Oxide Plated Axle Bearing Insert Mounted Bearing 2-1/2"UC213 40 Black Oxide Plated Axle Bearing Insert Mounted Bearing 2 1 2" Inch Inner Diameter UC213 40 Black Oxide Plated Axle Bearing Insert Mounted, Bearing is standard duty, bearing is Wide inner ring with spherical outer ring, Black oxide has certain properties and characteristics that makes it ideal for certain applications. It is used to add corrosion resistance and for appearance. UC213 40 black insert Bearing Cylindrical Carttridge Ball Bearing