1.High precision 2.High speed:400,000rpm 3.Long life:150hours 4.Low noise Deep-groove ball bearings for dental handpiece Type Size(mm)FeaturesLimiting Speed(rpm)Application for handpieceBore(d)O.D(D)Width(B)SR142-Z3.1756.35/5.972.38one-side of dust cover, groove350000~400000North Pole HandpieceSR143-Z3.1756.35/5.972.78one-side of dust cover, groove350000~400000German KovoSR143-ZT3.1756.35/5.972. ...