Galvanised Corrugated Fasteners. Also known as 'dogs' or 'wriggly nails'. various leg lengths 9mm 12mm and 15mm, adjust the tool accordingly. The width (crown) of the fasteners 25 mm (1 inch) all the way through regardless of leg length Red dye indicates the blunt side of the fastener ie the end that is loaded against the magazine. Uses: Mitered joints, butt joints. For bringing two pieces of wood together.