5 x 8 x 2.5 Shielded Wheel Ball Bearing One Bearing 5 x 8 x 2.5 Shielded Wheel Ball Bearing, this is a popular size that could be used in many RC Cars and Trucks or any application that uses this size 5mm x 8mm x 2.5mm. Bearing is made of Chrome Steel, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearing is pre-lubricated with grease.