3M™ Fire Barrier Cast-In Device Metal Deck Adaptors are one-piece plastic body adaptors for one-step firestopping on fluted metal decks. Installers simply snap a metallic or non-metallic 3M™ Fire Barrier Cast-In Device into the adaptor – no fasteners are required – and attach it to the metal decking before concrete slabs are poured. Adaptor/device assemblies are firestop tested up to 3 hours.