Dacatie Cavity Fire Barriers restrict the spread of smoke and flames within external masonry walls, as well as minimizing the effect of flanking noise pollution at wall junctions. Made from low resin, non-combustible rockfibre mineral wool insulation and are sleeved in polythene for on-site protection.These Dacatie Standard Firesock offer 1hr protection, are 1200mm long and available in 3 different section sizes.