The Halo series of bearings are a high quality steel/chrome bearing with metal shields. These bearings have been tested and proven by many racers. This is the common bearing used in the Team Losi XXXNT clutches (these are non-flanged, standard for the Drake edition)
1/4 x 3/8 x 1/8 Halo bearing by Avid Racing Concepts is the standard bearing for nitro clutches. Check your manual for the correct size for you vehicle if you are not certain.