The 5x14x5 ceramic series of bearings are a high quality steel/chrome bearing with metal shields and ceramic Si3N4 balls. These bearings have been tested and proven by many racers.
5x14x5 Metal Halo bearing by Avid Racing Concepts is a popular bearing for Tekin Pro4, Novak, and Neu-Castle motors. Check your manual for the correct size for your vehicle if you are not certain.