metal screw used for gypsum board material: steel size: 3.5x25mm 3.5x35mm and so on high strength metal screw used for gypsum board Drywall tapping screws are widly used for gypsum board Self tapping screw: Diameter: 3.5mm(#6),3.9mm(#7),4.2mm(#8),4.8mm(#10) Length: 25mm,35mm,50mm....Coating: Black Phosphated,Grey Phosphated,Zinc,Yellow Zinc,Packing: 1000pcs/box or 600pcs/box as your requirement.