Tire-pressure monitoring system from Mobile Awareness features pressure sensors that mount externally on the valve stem for ease of installation. Unit measures low and high pressure, plus tire temperature and slow leaks. The upgraded model is smaller, lighter, and can transmit farther, eliminating the need for a signal repeater, the company says. Battery life has been extended to seven to 10 years. Estimated list price range: $595 to $1,195, depending on tire configuration.