欧美性zoo_夜夜摸日日操_大胆顶级欧美aaa级_经典av三级_成人视屏在线_一级 黄 色 片69

Diamond segment and grinding wheel products are made of synthetic diamond and a variety of metal powders as a bonding agent. They are formed by cold pressing and hot pressing, and are not easy to fall off during use. It is assembled on various professional grinding wheel processing machines for the efficient grinding and polishing of the surface, inner hole and outer circle of grinding wheel products. It has the characteristics of good sharpness, long service life and high work efficiency.