Used for stitching metal or attaching to metal. A pre-drilled hole is required. Pan head for extra clamping plated in Trivalent Chromium (CR3) zinc 3 microns. 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