Firex 921 is a one part fire rated MS Polymer based sealant. The sealant is formulated to intumesce on exposure to high temperatures to form a fire and smoke resistant joint seal.
Specification Details for Geocel Firex 921 High Performance Elastometric Intumescent Expansion Joint Sealant (Sealants)
Please note that these product properties are not a replacement for the manufacturer's literature and it is always recommended that Geocel is consulted before specifying.