TORNADO FUEL SAVER -- EPA confirmed and proven to increase gas mileage by 1 to 2 miles per gallon; 3.125 in. diameter x 1.5 in. height; Includes full installation instruction; This economical air management system has a non-moving turbine shaped device with a unique set of airflow dynamics that creates a fast burning effect in the combustion chamber resulting to improved airflow and more efficient combustion; No maintenance necessary; Easy 3-step installation; With Tornado's limited lifetime warranty.