The CMT 791.010.00 is a 1/2 to 1/4-Inch Bearing. SAFETY RECOMMENDATIONS: be sure to keep the black shield right side up to correspond with the bearing rotation during reassembly. Features: * 1/2-Inch OD x 1/4-Inch ID Bearing What"s In the Box: * CMT 791.010.00 1/2 to 1/4-Inch Bearing