1 pack, 2.5 gallon prime guard ultrapure diesel exhaust fluid. includes a nozzle for an easy pour. environmentally friendly solution for selective catalytic reduction (scr) systems. meets the stringent iso 22241, aus 32 and din 70070 standards for purity and concentration. formaldehyde-free, nox reducing treatment specifically formulated for diesel engines equipped with scr systems. api certified for proper scr operation. meets or exceeds all epa standards.