17mm Bearing UCF203 Black Oxide Plated Insert + Square Flanged Cast Housing Mounted BearingsUCF203 17mm Mounted Black Oxide Plated Insert + Square Flanged Bearing One Bearing UCF203 17mm Mounted Black Oxide Plated Insert + Square Flanged Bearing, the inner diameter is 17mm. 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: UCF203 Bearing Black Oxide Plated Insert Type: Mounted Bearing Bolt Size: M10 Shaft Diameter: 17mm Basic