It requires two AAA batteries, which are included.
HSA/FSA Eligible Measures: oxygen level, pulse rate For children and small to medium sized adults Bright display that is readable from all sides One-button operation Automatic power off Includes 2 AAA batteries The GPD Health Pediatric and Adult Pulse Oximeter is designed to help you get easy, fast readings for your oxygen levels and pulse rate to help monitor a variety of conditions..