Ball Bearings 6703ZZ 17mm x 23mm x 4mm One Ball Bearing 6703ZZ, 17x23x4 mm dimensions, the 6703ZZ inner diameter is 17mm, outer diameter is 23mm and the width is 4mm, this is a popular size that could be used in many applications, Bearings are made of Chrome Steel and can rotate up to 23,000 rpm, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also the 6703ZZ bearings are pre-lubricated with grease.