E85 offers many benefits to performance enthusiasts and racers with its 105-octane rating, cooler engine temperatures, and cleaner emissions. The variations from pump to pump for street driving are negligible, but to the racer, even a small percentage change of ethanol can determine the outcome of a race if nothing is done to compensate for it. Consistency is especially important in bracket racing, where a win can be determined by thousandths of a second. E85 fuel is said to contain 85 percent ethanol and 15 percent gasoline, but the fuel mixture can vary anywhere from a low of 70 percent all the way up to 85 percent ethanol, depending on the place of refinement and the season of purchase. These Quick Fuel E85 fuel testers will let you know exactly what you are pouring into your tank. They are designed to help you calibrate your air/fuel mixture. Using the testers takes only a few moments and they are simple to use. First, you add water up to the first line on the Quick Fuel E85 fuel testers, and then pour in the E85 sample up to the second line. The ethanol absorbs the water and the gasoline floats on top, revealing a definitive boundary. This boundary will lie in the graduated area of the testers, giving you the percentage of ethanol in the E85 fuel. They come with a durable carrying case to keep them safe in any toolbox.