Trackball: Diameter:19.05,25.4,38,38.1,50.8mm, Grade:500-1000 The trackballs are widely applied in keyboard, surface smooth wear-resisting, not easy to scratch.Chemical composition (%)CSiMnPSCrMoNiCu≤0.08≤1.00≤2.000.045≤0.03018.0-20.0-8.0-10.02.25Nonstandard orders customized are acceptable.