Shield’s Diesel Exhaust Fluid is made from high purity synthetic urea and deionized water. It is a stable, colorless, nonflammable nontoxic fluid. This special formula will help in maintaining a functioning selective catalytic reduction (SCR) system. Reduces harmful nitrogen oxide emissions and even improves fuel efficiency. It is a simple to use, low cost, clean solution to meet the 2010 EPA clean air act requirements.