déctecte timidly ...

For the period: hats off for received less than 48 hours after order!
For the device itself, it is a simple gas detector and asks nothing more than to detect !!
That's what I did, upon receipt, into the holding P1 over a burner on my stove, I opened (partially and cautiously) without lighting the flame, of course ... ! the gas has begun to escape the kitchen.
Result: after 2 or 3 seconds, my nose detected the odor of gas. And after 10-15 seconds (only), the alarm will sound detector (not so strident it elsewhere, and I wonder if we would hear in located in another room, and another floor ????)
Conclusion: if you're in the same room where the detector is installed, it is not used much because your nose is much more sensitive and rapid (unless you have a cold ???) to detect the smell of gas.
If you are in another room (day) or bedroom (night), then this sensor becomes essential, especially to alert you during sleep and avoid tragedies ...! But check that the alarm is heard in these parts, which I doubt.
For my part, I intend to place a sensitive microphone transmitter (type wireless HF) near the gas sensor, and an RF receiver with portable small speaker to amplify the sound of the alarm (if it is activated) and be on to hear my speaker regardless of where I am in the house. This is the only way to make it really useful and detector.