marsboy Gas Alarm Detector Digital Display 9V Battery Back up Sensitive and Reliable - Advanced semiconductor gas sensetive element, Detects Natual Gas, LPG, Coal Gas ,Combustible Gases. Dual Power - plug in/electric and front load battery ensures continuous protection to make certain the alarm will work at all times, even during power outages. Easy to install and use - Plug-in unit with battery backup, the Digital LCD display shows gas concentration(PPM), When a dangerous level of gas is detected, the red light will pulse and a loud alarm pattern will sound. Smart - Alarm memory function and auto detect sensor failure. What you get - Product comes with 12-month warranty. 24/7 customer service available.