Flame Stop II is a water-based, post-treatment, interior/exterior fire retardant, and wood preservative that penetrates the material and bonds with the cellular structure. The penetrant protects the substrate by developing a self-extinguishing reaction when the treated material comes in contact with an open flame. When properly applied on certain untreated woods such as Douglas fir, the wood shall have a Class A rating. Flame Stop II contains polymers that maintain the fire retardation for up to five years for exterior applications. Flame Stop II is non-toxic, non-combustible, non-carcinogenic, easy to apply, and contains no PBDE's.