... threads "A","AB", Threads for chipboard screw,wood screw,drywall screw;Type "M","UNC","UNF","BSW"threads for Machine threads.Head typesHexagon ... 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 ...