This Finger Pulse Oximeter is the perfect choice for on-the-spot SpO2 and Pulse Rate testing. The unit's lightweight and small size means it can be easily carried in your pocket. The universal finger clip allows the oximeter to fit a range of finger sizes from paediatric through to adult and it automatically switches off when a finger is removed from the unit for more than 5 seconds. LED Display can be seen even in low ambient light levels. Lanyard and Batteries all included. This Finger Pulse Oximeter is approved by FDA (FDA 510K Number: K082641) and can be used without medical prescription by a variety of sports enthusiasts, including mountain climbers, hikers, skiers, bikers, and others interested in measuring oxygen saturation and pulse rate, it is not for a medical use.