Ball Bearings 3x6x2.5 With Ceramic balls Lot of 10 Bearings 10 Hybrid Ball Ceramic Bearings , this is a popular size that could be used in many application that uses this size 3mm x 6mm x 2.5mm, 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.