Wood to metal screws are made from C1022 steel, case hardened for fastening wood to steel or aluminum. The star drive flat head reduces camout and end load, handles greater torque than Phillips or square drive, and eliminates spinning and fastener damage. For star drive use a T30 drill bit (not included). Reamer wings drill through wood and snap off when they encounter metal. The #3 drill point penetrates up to 1/4 In. metal with no predrilling. Shank slot holds steel shavings and improves drilling action. Ideal for trailer beds and walls. All screws are 1000-hour salt spray test dacro coated. All Acorn International screws are packed 250 pieces.