1/2" Bearing UCF201-8 Black Oxide Plated Insert + Square Flanged Cast Housing Mounted BearingUCF201 8 Four Bolt Flange Unit with black insert 1 2" inch Inner Diameter UCF201 8 Four Bolt Flange Unit with Black Oxide plated Insert, bearing is Set Screw Type, Inner Diameter is 1 2" inch. Black oxide has certain properties and characteristics that makes it ideal for certain applications. It is used to add corrosion resistance and for appearance. Item: UCF201 8 black insert Ball Bearing Type: Flange Mounted Bearing Bolt Size: 3 8" inch Shaft