Color changing, lightweight oxygen meter is designed for non-medical periodic spot checks of pulse rate and blood oxygen saturation levels.. Color changing backlight indicates green for normal, yellow for caution, red for alert. Requires 2 AAA batteries (not included). Includes storage case. Intended use: For non-medical periodic check of heart rate and blood oxygen saturation level at home, and for sports and recreational uses such as mountain climbing, high altitude activities and running. Not intended to replace a doctor's visit. This fingertip unit should not be used for medical diagnostic and treatment activities without a doctor's guidance. Product Dimensions : 15 x 2.5 x 7.6 inches; 8.82 Ounces