... valve balls 2.Hardness:HRC58-62 3.Grade:G100 4.1/2",3/4" 1,1/4' 1,1/2' 1/2",3/4" 1 ... ,1/4' 1,1/2' ... special bearings & micro – ball for the electronics industry. 2. High accuracy & low noise motor bearing& household appliance bearings ... 3. High - speed, low noise special bearing 4. ...