As a nurse, I can tell you how important it is that when a patient has a lung disorder or in fact a lung disease the important of this little handheld device is. The SM-165 Santa Medical Finger Pulse Oximeter is FDA approved. It quickly and accurately measures your pulse rate as well as your blood oxygen levels (SPO2). When I worked, I would use a device like this daily when it came it measuring how well my patients were oxygenating. It has a bright LED display and shows your real time pulse rate, the SpO2 level and the battery level. I like that this device can read over a thousand readings, and can be used continuously as long as it is reading. It is light and compact, as well as can accommodate several different finger sizes. It as well comes with its own 2 AAA batteries, lanyard, and a case. I would highly recommend this product to anyone! Check out my you tube below to see it in action!