日韩超级波霸_最新中学生a片_日韩成人av在线看_欧美色青_可以直接看的av网址_日韩Av看片

The machine is designed to grind four straight grooves of equal angle, equal width, equal depth and equal length on the grinding wheel surface. The operating cycle is controlled by automatic program, and all the slotting actions can be completed by pressing one button.