glass beads 20-300mesh for sandblasting/grinding

glass beads 20-300mesh for sandblasting/grinding Glass bead for sandblasting:20-300mesh Roundness: 80% Refractive index: 1.5  Proportion: approx. 2.5  Coating type: According to international standards  Appearance: colorless, transparent ball, no visible bubbles and impurity.    Chemical compositions: SiO2: 70%-74% Na20: 12%-15% CaO: 8%-10% MgO: 1.0%-3.8% A1203: 0.2%-1.8% K20: 0%-0.5% Usages: sandblasting grinding lapping