This heavy duty tire inflator is rated for tire pressures from 20lb to 120lb. Anything lower (e.g. 12 pound garden tractor tires) can be inflated but not metered. The scale is retractable and surprisingly accurate for higher pressures than other gauges. This is a dual head chuck that can easily reach most dual tires. An adapter with an external thread is required to connect to an air hose (not included). It comes with four extra valve stem caps and inserts and an insert removal tool. Once the hoop is attached to the hoop, simply squeeze the handle to inflate it. Release the handle and the air gauge will show how full the tire is. Press the side button to remove the sensor and adjust inflation as needed. All in all, this is a good inflator.