... Steel drywall screw Material:steel Treatment:white zinc Head:hexagon head Size: M6*15, M6*20 Product name: ... chipboard screw, ball screw, hex head screwbolt screw, bolts and nuts, self drilling screw, self tapping screw, machine screw, furniture screwdrywall ... : CNC machine, automatic lathe, grinder, thread rolling machine, tapping /drilling machine etc 3) Measuring & testing equipment: Projecting ...