Features:1, Round style: 2.4bar 36PSI2, Material: Chromed brass3, Simply install on the air valve4, Easy to control and install5, Size: (Approx) 2.3 x 1cm / 0.91" x 0.39"6, Make the tire of your car more safe.7, Fit on any standard size existing tire valve stem8, Visually alerts you when the tire pressure is low to help avoid premature tire wear or blowout from under-inflated tires. Function:If the tire pressure is lower 15% than tire pressure standard, it will increase 6% fuel consumption, as well we double tire wear, thereby increasing the risk by 30%, but the tire pressure cap will remind your attention in this matter to ensure your safety and lower fuel consumption. Notice:1, Normal: in normal condition, transparent window show green color.2, Warning: the tire pressure is below 10% of standard (2.4bar), transparent window show yellow-green color, it should be promptly inflatable.3, Danger: about 25% less than the standard, transparent window show red-yellow color, it should be inflate immediately.