SP Firestop OSCB is installed horizontally and is suitable for cavity widths up to 600mm (OSCB 25) and 425mm (OSCB 44). The product is designed for use only with ROCKWOOL RAINSCREEN DUO SLAB or NyRock Rainscreen 032 and forms an open-state cavity fire barrier within a rainscreen cavity. The product is comprised of a continuous intumescent strip fixed to the leading edge of a foil faced stone wool barrier and encapsulated by a weather-resistant polythene sleeve. The combination of non-combustible insulation with an effective intumescent has been fully tested to ASFP TGD 19 and supports the construction of safe façade systems and aids the design of high-rise buildings over 18m in height while ensuring an appropriate open air space is maintained.