1-1/4" Bearing UCF207-20 Black Oxide Plated Insert + Square Flanged Housing Mounted BearingUCF207 20 Black Oxide Plated Insert + Four Bolt Flange Unit Set Screw Type 1 1 4" inch Inner Diameter UCF207 20 Black Oxide Plated Insert Four Bolt Flange Unit, bearing is Set Screw Type, Inner Diameter is 1 1 4" 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. UCF207 20 Black Oxide Plated Insert Bearing + Square Flanged Housing Flange