AVID - 5x12x4 Revolution
The Revolution Series bearings are a low friction bearing with several options to help satisfy anyone's desire. What makes this bearing unique is that it has a rubber seal on one side while having a metal shield on the other. Rubber seals are great protectors against dirt but the price is that they offer a little more friction due to the tighter seal.
5x12x4 Halo Revolution bearing by Avid Racing Concepts is a popular bearing for the Xray 808 clutch. Check your manual for the correct size for your vehicle if you are not certain.