The color coded tire pressure indicator cap takes away the worry about your tire pressure. At a glance you can see if the tire pressure is correct or if it has become lower than required. Low tire pressure leads to more sidewall wear, increased temperatures and uneven tire wear resulting ins shortened tire life and possible sudden tire failure resulting in a crash. Fill your tires to the manufacturer’s recommended pressure, install the color coded tire valve cap and see green. Leave the cap in place for future reference. If the tire pressure drops, the color yellow will appear (tire needs air) or the color red will appear (the tire is exceptionally under-filled). Easy to install, these caps replace the normal rubber protective cap. Just twist the caps on hand-tight (do no over-tighten) and enjoy worry free tire maintenance checks, better handling, longer tire life and better fuel mileage.