The 3/16 x 3/8 x 1/8 Halo series of bearings are a high quality steel/chrome bearing with black rubber shields. These bearings have been tested and proven by many racers.
3/16 x 3/8 x 1/8 is the common bearing used in the B4/B3/B2/XXX/XX/TC3/T4/T3 for hubs, wheels, and transmissions.