This portable, easy-to-use fingertip pulse oximeter accurately measures oxygen saturation and heart rate anywhere, anytime. Ideal for worry-free travel and doctor-advised exercise, it provides the double-security of knowing when to increase your liter flow as well as your resting and active pulse rates. It features a comfortable, ergonomic design with 2-way LED color display that's easy to read day or night, 2 digital accuracy, a symbol appears on screen when blood oxygen saturation levels become critically low, and a low battery signal. Accommodates finger widths from 0.3" to 1". Designed in drop-test durable plastic. Requires 2 "AAA" batteries (included) for up to 45 hours of continuous operation. 4"L x 4"W x 3"H.