self-tapping,with different sizs , materials, finishes and standards . self-tapping screwstandard : JIS , DIN . AISI, GB .material : carbon steel , stainless steel , alloy steel .class: class4 . class 8, class10.9,class12.9. grade2,grade5,grade8,...finish: blue zinc ,yellow zinc , black zinc , nickel and so on.We are professional manufacturer and exporter for different kinds of fasteners ,pipe ...