Ball Bearings 5x9x3 Lot of 10 Bearings High Quality 10 Ball Bearings for many YoYos, this is a popular size that could be used in many Yoyos that have 5 mm bore, or any application that uses this size 5mm x 9mm x 3mm, Bearings are made of Chrome Steel and can rotate up to 48000 rpm, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease, Bearings are packed 10 bearings in one plastic tube.