The 1.5x4x2 metal 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: 1.5mm (Inner) x 4mm (Outer) x 2mm (Width)
STANDARD: 0.05906" (Inner) x 0.15748" (Outer) x 0.07874" (Width)