This wouldn't be a complete test without tearing down the sensors. Both devices run on 3 AA size batteries. Both are also a great study in cost reduction. Neither sensor uses screws - they simply clip together.

First the Floureon sensor:

Top:

and Bottom:

Next the Kidde top:

and Bottom:

It was interesting to see how much larger the Kidde electrochemcial cell was compared to the cell in the Floureon device. Bigger doesn't necessarily mean better, but I did see that the Kidde sensor was serialized, with data printed right on the can. That suggests each cell is individually tested.

Overall, the Kidde seemed to be better assembled in terms of quality.

I wasn't able to read the part numbers on either device. The Kidde sensor was embedded in wax, while the Floureon had part numbers sanded off.