The Pulse Oximeter is designed for use by athletes, aviators, and those with respiratory or cardiovascular ailments, such as asthma or heart disease. The Oximeter is very easy to use, simply pinch the clamp, and insert your finger. Hold still and you will receive an accurate reading of your SP02 level (the amount of oxygenated hemoglobin in the blood), your pulse rate, and show the perfusion index (the amount of blood flow measured by the oximeter). You can also click the button again to cycle through the six different display modes. Each reading is displayed on a bright rotatable OLED screen that is very easy to read, even when sitting in the dark. The oximeter can store up to 8 hours of data, with data analysis occurring after monitoring for more than 2 hours. With a long 6 hour battery life the device will cycle off after no input for 8 seconds to conserve power. Small, compact, and very lightweight this oximeter is great for travel. *Batteries are not included.