UC204-12 Bearing for Universal ProductsOne New Aftermarket Replacement UC204 12 Radial Insert Ball Bearing Universal Fit The UC204 12 is a radial insert ball bearing (UC200 series) with a 3 4 inch bore and set screw locking, designed to mount directly onto a shaft inside a pillow block, flange block, take up unit, or similar housed bearing assembly. It features two set screws on the extended end of the inner ring used for holding onto a shaft. This UC204 12 insert bearing is self aligning