hex flat jam nut , with different size , material , standards and finishes . hex flat jam nutstandard : JIS , DIN . AISI, GB .material : carbon steel , stainless steel , alloy steel .brass , copperclass: class4 . class 8, class10.9,class12.9. grade2,grade5,grade8,finish:plain , black oxide , blue zinc ,yellow zinc , black zinc , nickel and so on. hex flat jam nut brass / copper