5 x 11 x 4 ABEC-5 Ball Bearings With Ceramic balls 10 Ball Bearings 5 x 11 x 4 ABEC-5 Ball Bearings With Ceramic balls, Bearings are made of Chrome Steel With Ceramic balls, each bearing has 2 Rubber Seal to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.