New. Clinically validated accuracy. O2 - Measures blood oxygen levels, an important indicator of respiratory health. Measures pulse rate. Auto shut-off. Works for adults and children 12 yrs old+. A key symptom of respiratory or blood circulatory illnesses is diminished lung function, which may lead to lower blood oxygen levels. This device measures blood oxygen levels. Simple finger clip design. Push button rotating display. Back-lit OLED display. Also great for athletes. Package recyclable. Helen of Troy cares about the environment, please recycle.