10x15x4 Revolution Bearings
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.
10x15x4 Revolution bearing by Avid Racing Concepts is the standard bearing for the Adam Drake 2 Losi truck in the rear hubs, Xray hubs and 1/8th scale on-road hubs. Check your manual for the correct size for your vehicle if you are not certain.