-Choose the correct metal screw to complete your project. SELF-DRILLING SCREWS should be used to attach wood or metal to metal without pre-drilling a pilot hole and should be used when fastening to 20 gauge steel or higher. SELF-PIERCING SCREWS should be used to attach thin sections of metal to metal, 20 gauge steel or lower and penetrate the metal exposing the protruding threads to limit potential backout. Specific self-piercing screw applications would apply to framing, lath, gutter and self-sealing screws.
7 x 7/16
Use #2 Phillips Drive Bit