Ball Bearings 6x12x4 Sealed Lot of 10 Bearings High Quality 10 Ball Bearings , this is a popular size that could be used in many application that uses this size 6mm x 12mm x 4mm. Bearings are can rotate up to 80,000 rpm, each bearing has 2 Sealed to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.