This small, portable, and easy to use unit comes in a small compact light weight carrying case. The unit has a stainless steel probe, a two meter length rubber hose, a rubber vacuum bulb, and a carrying strap. The unit monitors in percentages & will go down to 2% (200ppm). The hand held unit can be used in two different modes: 1) The continuous monitoring mode which can be done simply by connecting the rubber tube to the exhaust port of what you are purging and allowing the exhausted gas to flow free over the senor. 2) The monitor can also be used in the sampling mode. The stainless steel probe is inserted either into the area being purged or the exhaust port. The rubber bulb is then to draw a sample of the gas across the sensor.