High Quality Midwest Handpiece Dental Bearing Straight:Ceramic:Stainless Steel:ABEC-7 Solid Si3N4 Ceramic Balls High quality and Speed Midwest Handpiece Dental Bearing ABEC-7 Bearing that fits most of the Midwest Handpiece applications. bearing is closed from one side and it is Stainless Steel bearing with solid SI3N4 Ceramic Balls, bearing is one side Metal shield, Bearing is made of Stainless Steel and has Solid Ceramic balls Si3N4 (Silicon Nitride), the cage is made of Torlon for lowest fricion and highest speed.