Calibrating the right air/fuel mixture is important to gain proper power and efficiency from your carburetor and engine. But for vehicles running E85 fuel, proper calibration is difficult if you don't know the exact percentage of ethanol-to-gasoline in the fuel. Because E85 fuel can vary in the amount of ethanol and gasoline mixture, Holleys E85 Checker is an essential tool that can instantly determine the ratio in the E85 fuel youre using. Holleys E85 Checker fits in your pocket or tool box, and is easy to use. Simply add water to the first line on the E-Checker and then pour in the E85 sample to the second line. Once the water is absorbed, the Holley E85 Checker will indicate the amount of ethanol in the fuel. With the added benefits of 105 octane, cooler engine temperatures and improved emissions, Holleys E85 Checker can make a winning combination with any of Holleys E85 calibrated carburetors and fuel-pumps for your vehicle.