688ZZ Ball Bearings 8mmx 16mmx 5mm 10 Bearings 10 Ball Bearings 688ZZ are a popular size that could be used in many application that uses this size 8mm x 16mm x 5mm. Bearings are made of Chrome Steel, each bearing has 2 Metal Shield to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.