3/4" Bearing UCFL204-12 Black Oxide Plated Insert + 2-Bolt Flanged Housing Mounted BearingUCFL204 12 Black Oxide Plated Insert Mounted Bearing 3 4" Inch Inner Diameter One Bearing UCFL204 12 Black Oxide Plated Insert Mounted Bearing, measures an inner diameter of 3 4" Inch. UCFL204 12 Black Oxide Plated Insert Bearing + 2 Bolts flanged Housing. Black oxide has certain properties and characteristics that makes it ideal for certain applications. It is used to add corrosion resistance and for appearance Mounted Bearings Bolt Size: 3 8" Inch