From Forgefix
Features/Benefits Corrugated Roofing Nail, Extra Large Head. Finish: Galvanised. Twisted shank for increased holding power. Absorbs movement when expanding and contracting in the varying climate. The extra-large head distributes the load directly underneath the top of the nail, corrugated roofing stays firm and secure. Galvanised for increased durability. Most popular nail used when fixing corrugated roofing.