... screw,drywall screw;Type "M","UNC","UNF","BSW"threads for Machine threads.Head typesHexagon head,Mushroom head,Pan head,Countersunk head ... can pass.4.Quality equipments and QA staffs random check or total check products in each procedure,Items will be qualified when ... used in most of places such as drywall,concrete,chipboard,machine,wood...2) Main export market:North America,South America,Eastern ...