3/4" Bearing UCP204-12Black Oxide Insert + Pillow Block Cast Housing Mounted BearingUCP204 12 Black Oxide Insert + Pillow Block Cast Housing Mounted Bearing Set Screw Type High Center Height 3 4" inch Inner Diameter UCP204 12 Black Insert Pillow Block Bearing, UCP204 12 is Set Screw Type High Center Height, Inner Diameter is 3 4". Black oxide has certain properties and characteristics that makes it ideal for certain applications. It is used to add corrosion resistance and for appearance. UCP204 12 Black Oxide Insert + Pillow Block