Firemaster 520, tetrabromophthalic based diol, is a low viscosity, high reactivity flame retardant primarily used in Class 1 and Class 2 rigid polyurethane foam. The higher reactivity profile of Firemaster 520 offers greater processing latitude and improved polymer curing in comparison to PHT4-Diol. Other application areas include polyurethane RIM, elastomers, coatings, adhesives and fibers.