Handpiece Bearing for Bien Air 1 feature of smooth 2 high precision level ABEC 7 ... level P4 (ABEC 7),usable for various models of Bien-Air high-speed dental turbine handpieces. Materials of Bearing Parts: · Outer ring ... d3,175*D7,938*B3,571mm· Rotating speed 350.000-450.000 rpm under air-pressure of 200-250Kpa· Working life for ... details, please kindly contact us. Thanks! Handpiece Bearing for Bien Air