The ROCKWOOL SP FireStop Slab is designed to use with SP FireStop Fixing brackets to create the SP FireStop System. The FireStop Slab is medium density with foil facing to both sides. Cutting lines on the slab aid in accurate installation. The complete SP FireStop System resists the passing of smoke and provides up to 2 hours fire resistance (in voids of up to 600mm). Protecting against both movement of +/- 3% and also acoustic loss, the SP FireStop slab significantly reduces the levels of sound transmission through wall and floor cavities.