... optional2.Styles:OPEN,Z,ZZ,RS,2RS,2RZ3.Tolerance:ABEC-1, ABEC-3, ABEC-5, ABEC-74.Vibration :V4, V3, V2, V15.Radial play ... , PEEK or (stainless) steel8.Application: doors, windows, wheel chair, skating shoes, textile machine and so on. bearings for windows and doors