FIREZERO WIDE STOPPING strips prevent the spread of fire & smoke between compartments such as on top of masonry walls under soffits, between walls and steel work and between masonry & roofs.; above a partition system, as an expansion joint requiring a fire railing in a masonry wall within a metal cladding system and numerous similar applications. FIREZERO WIDE STOPPING also aids the reduction of sound transmission. For gaps above 150mm deep use FIREZERO Multi App Slab (data sheet 728)