The 12x28x8 Metal bearings 6001ZZ are a high quality steel/chrome bearing with metal shields. These bearings have been tested and proven by many racers. Check your manual for the correct size for your vehicle if you are not certain.
METRIC: 12mm (Inner) x 28mm (Outer) x 8mm (Width)
STANDARD: 0.47244" (Inner) x 1.10236" (Outer) x 0.31496" (Width)