UCFA205 Black Oxide Plated Insert Bearing Adjustable Flange Cartridge Bearing Unit 25mm Mounted BearingsUCFA205 Black Oxide Plated Insert Bearing Adjustable Flange Cartridge Unit 25mm Inner Diameter UCFA205 Black Oxide Plated Insert Bearing Adjustable Flange Cartridge Unit, the inner Diameter is 25mm. 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: UCFA205 Black Oxide Plated Insert Bearing + Flange Housing Type: Adjustable Flange