... :Self tapping threads "A","AB", Threads for chipboard screw,wood screw,drywall screw;Type "M","UNC","UNF","BSW"threads for ... testing report . Almost each year ISO Quality person come into factory for Supervising inspecting. "integrity, in accordance with the national ... in most of places such as drywall,concrete,chipboard,machine,wood...2) Main export market:North America,South America,Eastern ...