The caps use LEDs combined with a sensor that causes them to blink when tire pressure falls below 95% of ideal. The system would make it possible to do a simple walk-around and know if your tires are properly inflated. Though you might think that's as easy as looking at the tires themselves, modern tires, especially low-profile radials with stiff sidewalls, don't show low-pressure symptoms as clearly as older tires once did.
Benefits of proper tire inflation are well known, including longer tire life, better fuel mileage and less chance of a blowout due to overheating or forcing the bead off the rim.
Pricing for the caps starts at £20 (US$40) for the standard version, while anti-theft caps cost £22 (US$44). Given that the blinking caps will draw attention to themselves whenever pressure runs even 5% low, it seems advisable to spend the extra 10% for the anti-theft version - especially on tractor-trailer rigs that could require as many as 10 or more of the caps.