bugle head drywall screw material: carbon Diameter: 3.5mm(#6),3.9mm(#7),4.2mm(#8),4.8mm(#10) cross bugle head drywall screwmaterial ... : 1022A medium carbon steel, hardenCoarse thread, bugle head screw for general purpose interior wood applications Diameter: 3.5mm(#6), ... " Coating: Black Phosphated,Grey Phosphated,Zinc,Yellow Zinc,Decromet Drywall Screw