Jam Nut Hex Thin Nut Wenzhou Jianhong Machinery Co., Ltd. Base Info Material:Carbon SteelType:Hexagon HeadHead Style:HexagonalStandard:DIN439, DIN936 or Custom-Made Sizes. Description Pre:Hex Slotted Nut/ Castle Nut Next:Mushroom Head Nib Bolt (guardrail bolt)