BlueDEF DEF002 Diesel Exhaust Fluid is a non-toxic solution used in medium and heavy-duty engines to reduce harmful emissions. It's composed of 67.5% purified water and 32.5% ultra-pure automotive-grade urea. When injected into the exhaust, it converts harmful NOx into harmless nitrogen gas and water vapor. BlueDEF meets ISO Standards 22241 and is API certified, ensuring high quality and safety. It's stored in a dedicated tank next to the fuel tank, and the DEF gauge indicates when a refill is needed.