Perimeter Solutions makes specialty chemicals and services for firefighting and niche industrial applications. The core business — roughly 79% of revenue — is fire retardants and firefighting foam, sold under the Fire Safety segment. Fire retardant is a chemical applied ahead of active wildfires to slow their spread, delivered primarily by air tankers. Perimeter doesn't just sell the chemical: it designs, builds, staffs, and operates the mixing, loading, and storage equipment at roughly 60 staffed air tanker bases in the U.S. and Canada, with equipment at over 100 bases globally. This bundled product-plus-service model is central to the business and functions as a near-irreplicable barrier to entry. The U.S. federal government (USDA Forest Service and Bureau of Land Management) is the dominant customer. Perimeter has deliberately shifted its contract structure toward fixed-fee service revenue to reduce exposure to year-to-year variation in fire season severity. Firefighting foam — primarily fluorine-free suppressants for petrochemical facilities, airports, and military installations — is the other major Fire Safety product, benefiting from the regulatory transition away from PFAS-containing foams. The Specialty Products segment (~21% of revenue) includes Phosphorus Pentasulfide, an input for lubricant additives used in internal combustion engines, and IMS, which makes niche printed circuit board components for aftermarket repair in defense, industrial, and energy systems. Perimeter's M&A strategy targets small, essential, non-discretionary industrial products with high free cash flow conversion, recently adding MMT, which makes machinery for medical device manufacturers.