The PAL-Urea is specifically designed to measure the Urea concentration of Diesel Exhaust Fluid (DEF), also known as AdBlue* in Europe.Already proven in Europe as the only reliable, go-to instrument for easy and accurate checks, the PAL-Urea is now available in North America in time for new 2010 EPA regulations on diesel emissions. DEF needs to have a 32.5% Urea concentration to work effectively in SCR engines.Make sure that the DEF that comes out of your pump and into your tank is pure in quality and safe from potentially harmful additives by using the only digital hand-held refractometer already trusted by European consumers.