... specification:M6-M24 3.Standard:non-standard Zinc Plated Hex Head Roofing Screw Our company is specialized in the production of ... system 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. Zinc Plated Hex Head Roofing Screw