PlyFast Double Lock Nail consists of a precision formed tube and disk made from coated steel to prevent corrosion. The tube is shaped to easily penetrate decking and existing membranes. The disk is securely clamped to the tube and rib reinforced to resist cupping. Locking Staple: Precision formed from stainless steel wire. Designed to attach base sheet, recovery board, and insulation to lightweight insulating concrete, structural wood fiber, and poured gypsum roof decks.