Combination Natural Gas and Carbon Monoxide Detector Plug in 2-in-1 Co Detector and Combustible Gas Detector,Propane,LPG,Gas Leak Detector for Kitchen/Home.

It functions as expected, and the volume is loud.

I like that this unit sounds the carbon monoxide alarm at more conservative (lower) levels than the standard UL detector thresholds. I also tested my unit with both CO and gas from the stove and both worked as expected.If anyone wants to know how to test for CO, I got this procedure from a CO meter vendor. Light a wooden skewer or match on fire, blow it out, and then put the smoldering stick under a glass bowl or something similar. The smoke from the smoldering will have a high concentration of CO and the reading should climb pretty quickly, as you can see in my pictures. You might also want to do this outside - my house smelled like a camp fire for a couple of hours. LOLDo NOT test CO detectors using car exhaust! Car exhaust fumes have a very high level of humidity and can ruin CO detectors.

These things are meant to be outlet powered, they indeed do work, i tested them by putting them near my vehicle exhaust. The alarming is easy to understand and plenty loud enough to hear in a home. This is not for a loud factory however. I can hear it from another room in my home easily if the environment is relatively quiet. If your power goes out, the 9volt battery lasts only about 3 hours, then the device trips up and may falsely alert, or perpetual reboot. we discovered this during a power outage after a hurricane and it scared us into believing we had issue. I had to use a secondary hand-held device to repeatedly safety check.

[Update January 2023]After barely 3 years, this alarm is completely useless. I does not register or alarm to propane at all. (Yes, it says "natural gas" but natural gas detectors also pick up propane, when they're working.) The carbon monoxide alarm did go off, but that was triggered by some household cleaning product. Very disconcerting, until the second time when it was clear the cleaning product was setting off the alarm rather than some source of CO of which there were none at the time.Gas and CO detectors do usually have a limited life, but there's no indication on this device of what that might be, and in any case it should be considerably more than 3 years. For that matter, it may have failed within the first year for all I know.Dropping the rating to 1 star for the false sense of security this piece of junk provides.[Original Review]This is a nice, compact CO and flammable gas detector. I bought it to install in the kitchen, primarily to detect any propane leaks from the stove. Some of the other reviews said that this device doesn't detect propane, so the first thing I did was test it by comparing to a calibrated gas detector that reads propane concentration in parts per million. This alarm went off when the other meter read about 4000 ppm. (This wasn't a very precise test, as I just pointed an unlit propane torch at the two meters sitting side by side.) The lower explosive limit for propane -- the lowest concentration at which an explosion is possible -- is 2.1%, or 21,000 ppm, so this is alarming at well below the danger point. Note that 4000 ppm smells like *a lot* of gas; the other reviewers probably just didn't get a high enough concentration to set off the alarm.The voice annunciator is nice because it tells you if the alarm is going off due to CO or gas. I took off one star because the alarm itself isn't very loud -- it'll certainly get your attention if you're in the same or next room, but probably wouldn't wake you up if you're not sleeping close by. It's not nearly as loud, for example, as typical smoke detectors or a different, name-brand CO/gas detector that I also bought.

Seems to work. Have not noticed carbon monoxide yet.

Worth the cost. I have purchased the same calendar 3 yrs in a row

I cannot figure out why the manufacturer put the outlet cord on top of the detector! When you hang in wall the cord weighs the detector down and makes it hang crooked. And if you need to install near ceiling this cord is sticking upward and weighing the unit crookedly. Plus the cord is not long enough to reach the outlet. You are better off buying detectors that use batteries.

This thing is awesome! I bought it cause I live in a RV and there are lots of gas things going on in an RV. One time I was spraying too much of an aerosol chemical down the hall and this thing let me know about it. I didn't realize the spray I was using, had a gas propellant and I had unloaded clouds of it and it was unhealthy. Luckily this thing stopped me from my mad chemist disaster that was potentially dangerous. Another time I had a clogged vent pipe for my RV holding tank. Methane gas was accumulating and it let me know. One time I had a Kerosene heater going, in a power outage during winter, and this thing let me know when the carbon monoxide levels were unacceptable. I'd say I've gotten my money's worth and it keeps me safe. It has a nice loud alarm that sounds like a cop about to pull you over. It isn't as loud as a typical shrilling smoke alarm but you will definitely hear it.