Slime 20089 2 Magnetic Pencil Tire Gauges 10-50 PSI with Bonus Aluminum Valve Caps Designed to ensure proper tire pressure and get the most out of the gas Offers 3.3 percent of gas mileage improvement Keeps the tire inflated to maintain proper pressure This gauge is a fuel saver pack and is perfect for the glove box Could be stored inside the gas can and satisfaction is guaranteed