3v lithium non rechargeable button battery.
WARNING: KEEP OUT OF REACH OF CHILDREN. Button Cell Batteries are Hazardous (new or used). Keep batteries away from children. These Batteries can cause severe or fatal injuries within 2 hours or less if swallowed or placed inside any part of the body. Medical attention should be sought if it is suspected a battery has been consumed or inserted; Call the 24-hour Poisons Information Centre in Australia on 131126 or New Zealand on 0800 764 766 or contact your country's emergency department.