Automotive Upgrade Technology's Air Alert is a device that alerts drivers and maintenance personnel when a vehicle's tires are getting low. It immediately flashes brightly when pressure has dropped 4 psi from the original pressure. Air Alert is a small valve cap that replaces the standard tire valve cap. The flashing is visible from any angle when approaching the vehicle. The cap's battery life has approximately 2 years in standby by mode (with correct tire pressure) and up to 3 weeks of flashing (with incorrect tire pressure).