PEAK Blue Def Diesel Exhaust Fluid is a remarkable and essential solution comprised of 67.5 percent purified water and 32.5 percent ultra pure automotive grade urea. It does not serve as a fuel or fuel additive, but rather acts as a powerful catalyst in the exhaust stream, converting harmful NOx into harmless nitrogen gas and water vapor - both natural components of the air we breathe. This high-quality product meets ISO Standards 22241 for purity and composition and is certified by the American Petroleum Institute (API).