Used for stitching metal or attaching to metal. A pre-drilled hole is required. Pan head for improved clamping. Pan head for extra clamping Plated in Trivalent Chromium (Cr3) Zinc 60 self-tapping thread for ease of insertion Manufactured to BS 4174:1972" Gauge: 4 Length inch: 1/2 Thread Dia. mm: 2.9 Length mm: 13 Head Type: Pan Recess Type: Pozi Point Type: AB Point Driver Bit Size: PZ1 Finish: Zinc & Clear Cr3 Material: Carbon Steel Timco Self-Tapping Screws - PZ - Pan - Zinc (Size 4 x 1/2 - 200 Pieces) in Silver