1.By compression strength: 52MPa(7500psi), 69MPa(10000psi),86MPa(12500psi),103MPa(15000psi).
2. By volume density: Low-density, medium-density and high-density.
3. By specification: 6-12mesh, 8-16mesh, 12-18mesh, 12-20mesh, 16-20mesh, 16-30mesh, 20-40mesh, 30-50mesh, 30-60mesh, 40-60mesh, 40-70mesh, 70-140mesh, etc.