Test for clogged or obstructed catalytic converters and mufflers. Fast and easy to use. Threads into Oxygen Sensor Port. Kit includes 12mm and 18mm adapters to fit most domestic and importaed vehicles. Gage measure 2 ½� diamter and has dual scale: 15 PSI and 1.00 Kg/Cm2. Hose is 41� long, No need to tap into exhause system then reseal holes afterwards. Packed in a vinyl pouch for store display and toolbox storage. Complete with instructions.