Thermocare Heart rate Pulse oximeter fingertip TP JZK-303 is easy to read colour display. For all those medical professionals, students, or home owners who are seeking a high quality and efficient fingertip pulse oximeter, this is an ideal pick! This finger pulse oximeter functions by shining light through your finger. Features: One button operation Automatic power off Includes 2 AAA batteries HD LED display (2 Colors) Oxygen Saturation Range 0 - 99% to100% Spo2 Operational LED Lights –Yes Wavelength of LED 660 660 Red Light, 940 940 Infrared Light