5 x 11 x 4 Premium ABEC-5 Stainless Steel Ball Bearing with Si3N4 Ceramic Balls (Silicon Nitride) 5 x 11 x 4 Stainless Steel Ball Bearings with Ceramic Balls Premium ABEC-5 quality, this is a popular size that could be used in many application that uses this size 5mm x 11mm x 4mm. Bearing is made of Stainless Steel, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, Ceramic Balls are the highest standard of balls that can make your bearings live at least 5 times more than any other bearings.