For most of skateboard bearings ,they are produce with Chrome steel rings ;
For cage ,there are normal nylon cage , Dupont nylon cage and steel cage , and for cage ,they are some different too ,with normal type or stronger one ;
For balls , there are steel balls and ceramic balls ( white ZrO2, and black Si3N4) ,MKL Bearings can produce with standard with 7 PCS balls ,we also have design with 6 bigger balls ,you can choose what you need .
MKL BEARINGS are professional factory to produce 608 and 627 bearings ,we can produce with customized service , for more informations just feel free to contact with us .