Slime's Pencil Tire Gauges are the ultimate solution to checking your tire pressure on the go! This pencil tire gauge measures from 10-50 psi and comes with 4 bonus valve caps! Available in a variety of color options: Black, blue, silver, orange, red, and green. You can improve your gas mileage by around 3.3% by keeping your tires inflated to the proper pressure. Under-inflated tires can lower gas mileage by 0.4% for every 1 psi drop in pressure of all four tires. Properly inflated tires are safer and last longer.