Fixing SP/S The installation of Rockwool Firestop SP60 and SP120 slabs necessitates the use of brackets. They're made to fit cavities up to and including 400mm in diameter. These bracket clips have a L shape to them. The leg with the angled point is 300mm long and impaled into the fire stop's base. These brackets are essential to preserve structural stability while also preserving the fire rating of the items utilised. The SP/S Fixing Brackets should be trimmed on site as needed to provide for at least 75 percent Firestop penetration.