Great for anatomy and physiology classes! Just place the pulse oximeter on a fingertip, press the button, and read both heart rate and blood oxygen saturation level in seconds. Digital display is easy-to-read with adjustable brightness and direction and can be switched to show perfusion index. Ranges for both heart rate and oxygen level are broad enough to allow resting and active measurements. Heart rate range is 30–240 beats per minute; oxygen saturation range is 35–99%; and perfusion index is 0–20%. Alarm will beep if oxygen saturation is below 90% and if the heart rate is above 120 bpm or below 50 bpm. Automatic shut-off feature preserves battery life. Includes lanyard, fabric storage case, two AAA batteries, and instructions.