have an older vehicle that doesn't have the computer telling you the tire pressures, and want to know fast and easy if the tires are still correctly aired up?

TPMS sensors are pricey. A couple hundred each last time I saw one sold. And without a cars computer to interact with the sensor, the next best thing are these! Cool idea!

Found at SEMA. Best place to look though new gizmos, gadgets, and products fro vehicles