1.low noise,low libration 2.seals type:open,seal,shield 3.high-end technology The same size can be made of ... : Open Bearing, Z, ZZ, RS, 2RS,TTTolerance codes: ABEC-1, ABEC-3, ABEC-5, ABEC-7Vibration level codes: V4, V3, V2, V1Internal clearance ... , SS697 RS, SS697RS, SS697-ZZ, SS697 ZZ, SS697ZZ, SS697 Z deep groove ball bearing 697