Carbon Steel Hex Head Roofing Screw 1.Head type:Round head 2.Thread specification:M6-M24 3.Standard:non-standard Carbon Steel Hex Head Roofing Screw Our company ... standard, the surface, galvanized, environmental protection zinc, black.Round head thickness, burr, can provide supporting square nut.Spectations:1)Size ... to your quantity.Welcome for your contacting. Carbon Steel Hex Head Roofing Screw