This is a portable pulse oximeter with heart rate monitor function in a single gadget. It measures your heart rate using a technique called plethysmography and the saturated level of oxygen in your body using photoplethysmography.
These methods involve illuminating your finger’s skin to measure changes in the light absorption.
Specifications:
-LED display
-Color: Blue, White
-Made from hard molded ABS
-Powers from 2 AAA alkaline batteries
-Optical Sensor: Red Light wavelength 660nm, Infrared wavelength 880nm
-Size: 58 x 32 x 34 mm.
Read more about it at Chinavasion and get one for $33.74.