PEAK BlueDEF is a mixture of 32.5% high purity synthetic urea and 67.5% deionized water that is used in Selective Catalytic Reduction (SCR) systems on diesel engines. DEF is the primary ingredient used to help convert NOx to harmless nitrogen and water. BlueDEF is stable, colorless, non-flammable and is classified as minimum risk for transportation. BlueDEF conforms to the ISO-22241-1 specification for DEF, is API registered and meets or exceeds OEM specifications. PEAK BlueDEF's exclusive triple-filtered formula ensures the highest product purity. Every batch is guaranteed pure.