Reflective glass beads for road marking Appearance: Colourless and transparent ball, no visible bubbles and impurity. Spherical beads:≥80%(600< Sieve size< 850um，spherical beads≥75%) Density:2.4-2.6g/cm3 Refractive index:Nd≥1.50　 Glass bead composition:The glass bead is made of sodium and calcium. SiO2＞68% Glass beads for coating. GlaTechnical references Appearance: beads with round ball shape and no visible impurity. Refractive index:＞1.5 density:2.4-2.6g/cm3 SiO2 content:≥68%ss beads for coating.