Features: 1) Made of alumina ceramic material 2) Fired through high temperature 3) Progress: grind, polish 4) High intension 5) Solid-resist 6) Alkali-resist 7) Un-knit and velvet surface 8) Good airproof capability 9) Good grind-resist capability Packing: 200pcs/small carton 20 small cartons/big carton Outer carton size: 35 x 35 x 25cm G.W.: 25kg