The 8x16x5 688ZZ Halo series of bearings are a high quality steel/chrome bearing with metal shields. These bearings have been tested and proven by many racers. Please check your manual to see if these are bearings you need to use.
METRIC: 8mm (Inner) x 16mm (Outer) x 5mm (Width)
STANDARD: 0.31496" (Inner) x 0.62992" (Outer) x 0.19685" (Width)