Available as a self-installable external sensor kit, nonda’s Smart Tire Safety Monitor features a USB-powered receiver with 4 external sensors that transmit data via Bluetooth directly to the ZUS app. Showing the tire pressure for all 4 tires in real time, the monitor can quickly detect punctures and/or excess temperature, giving both a visual and audible warning to alert the driver of possible tire failure. While the receiver utilizes a USB port, it does come with a USB output port for charging your mobile devices or GPS unit. As a result, you never lose a USB port.Box Includes:sensor x4receiver x1anti-theft lock x4installation kit