PHOS-CHEK^® 259-Fx is an ultra-high visibility solution. It is a powder concentrate that mixes readily with water by agitation or PHOS-CHEK eductor-mixing systems. PHOS-CHEK 259-Fx provides superior visibility in the air and on the ground, but slowly fades with exposure to sunlight. It has been specifically formulated for use in fixed-tank helicopters and exhibits extremely low corrosion to magnesium and other metals. It can be applied through many means including buckets, airtankers and through ground application.

PHOS-CHEK 259-Fx is an all phosphate, gum thickened, low-viscosity retardant that provides highly effective and accurate aerial drops. The elastic nature of PHOS-CHEK 259-Fx solution improves aerial delivery performance by reducing drift and evaporation. This results in increased fuel coverage, wrap around and penetration through canopy and ladder fuels.