The Halo series of bearings are a high quality steel/chrome bearing with metal shields. These bearings have been testedproven by many racers.
12x21x5 Halo bearing by Avid Racing Concepts is the standard outdrive bearing for nitro touring cars8th scale onroad cars such as the Kyosho RRR, Mugen MRX4,Serpent 710. Check your manual for the correct size for you vehicle if you are not certain.