5 x 10 x 4 Shielded Ball Bearing One Bearing 5 x 10 x 4 Shielded Wheel Ball Bearings for many applications, this is a popular size that could be used in many RC Cars and Trucks uses this size 5mm x 10mm x 4mm. 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.