CO Detector,Wewalab Carbon Monoxide Alarm, Carbon Monoxide Gas Detection,LCD Portable Security Gas CO Monitor,Battery Powered (Battery not included) (A)

Rubbish. As noted in another review, the positive terminal fails to make correct contact with the battery. I bought 2 of these and the defect is the same in both. Not happy as this device is critical for safety at home. I'm not comfortable jury-rigging the contact to make it work as it's entirely possible that it could fail again at a later time and not be noticed. Not to mention that this calls into question the engineering quality as a whole, if they can't get a rudimentary component to work correctly.Frankly this device should be pulled from the market.

Agree with Others who gave low ratings, there is poor quality control wrt the positive terminal AA battery contacts! I stretched the positive wire contacts so the positive terminal of the three AA batteries made good contact and the unit was no longer dead - initially it was DOA (dead on arrival).So if you want to keep your DOA unit stretch the positive terminals for good contact and it may spring alive as mine did. But come on Chinese manufacturer, one should not have to do this -

Don't buy this one. I purchased it along with a Kidde KN-COB-B-LPM which is better. The Kidde does not have the ppm readout, but the readout doesn't give a reading anyway unless the alarm sounds. This unit was dead on arrival and I discovered it was due to poor engineering on the part of the positive battery contact. The spring is quite flat at the positive terminal (flat spiral) and the battery can keep from making contact because of the thickness of the plastic battery stop unless you bend the contacts up a bit with a small screwdriver. I'm OK with that, but the killer for me is that the alarm is quieter than the Kidde. Update: I think this one is an earlier revision. I bought a similar one on e-bay for near half the cost. The chassis molds are almost identical but they resolved the thickness issue and mounted the siren in a better location. Other minor PCB changes and LED changes. The Amazon one I received has a clear lens for colored surface mount LED's while the one from e-bay are not surface mount. This of course is minor. It is also quieter than the Kidde. Upgrading to two stars though.

These work fine after a little modification. When we first received these detectors, I put the batteries in and had no power. We purchased three units and all three had the same problem. After about thirty minutes of troubleshooting I figured out it was the contact between the battery and the + terminal on the unit itself. I ripped a small strip of aluminum foil and stuck it between the contacts and it fixed the problem for all three. This really should be addressed by the manufacturer.

Ordered this and wanted it so bad for our home. Got it and first of all it said 1- 9 volt battery on box. Got the battery and opened the box and got it out. It takes 3 AA batteries NOT a 9 volt that stated on the box. We were to slide it to the on position, but the thing wouldn’t turn at all. Tried several times and several different people tried to turn it. The darn thing would not budge to on position. Anyway sending it back right away. Terrible product.

This unit came DOA, inferior engineering causing the battery not to make contact. The CO display is really useless because it shuts off and will only come on if alarm is triggered, at which point it is pointless

As of Dec. 2017, they are still selling units that do not turn on until I bent the positive battery terminal at least 45 degrees. After I did this, it appears to work fine, but I can't recommend purchasing this unit until the flaw is fixed at the factory.

Not sure why this detector needs so much power, but I even bought lithium batteries for it and it went though them in around 6 months. Threw it in the junk drawer.