This is the 1/4 x 3/8 x 1/8 Flanged Halo Metal Bearing from Avid Racing.
The 1/4 x 3/8 x 1/8 Flanged Halo bearing by Avid Racing Concepts is the standard bearing for axles in 1/12th scale cars and was used in the Team Losi XXXNT clutches. 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. Check your manual for the correct size for your vehicle if you are not certain.