hex cap screw ,with different sizs , materials, standards and finishes . hex cap screw material : carbon steel , stainless steel , alloy steel .class: class4 . class 8, class10.9,class12.9. grade2,grade5,grade8, A2-70, A4-80 A193 GR.B8, B8Mfinish: plain, black oxide .blue zinc ,yellow zinc , black zinc , nickel and so on.