Advanced level protection, with a digital display, visible even in low light conditions. The illuminated digital display shows carbon monoxide levels from 001-999PPM (parts per million). A green LED light blinks every 30 seconds to indicate that the device is working properly, while a red LED light pulses along with an audible alarm when high levels of carbon monoxide are detected. Compact, lightweight, and easy to operate. Operates with 3 1.5V AA batteries (not included). The package includes: - 1 alarm - 2 screws and 2 wall plugs.