6708-2rs Sealed Ball Bearing, Bearing inner diameter is 40mm, Bearing outer diameter is 50mm and Bearing width is 6mm, 6708-2rs bearings is a popular size that could be used in many RC Cars and Trucks, Bearing is made of Chrome Steel, each bearing has 2 rubber Seals to protect the bearing from dust or any possible contamination, also bearing is pre-lubricated with grease.