In a week it broke. I opened it and due to the vibrations of the bike (city bike), the cable had come loose in the speaker. Its sensitivity, although initially good, does not work properly after my intervention. In general, you get what you pay for, but I wouldn't buy it again.

I have put it on my machine and it works perfectly, and the sound it produces is very deterrent.

It works great for the bike,
the only drawback was the high battery consumption,
but with a simple switch (on-off) that I added, that was also solved (from lasting 2-3 weeks it reached 6 months and !!!)

I like it, it activates immediately, it is definitely a security measure that you want to have on your bike/scooter, it produces a satisfactory sound, not very loud though, but it can scare someone who wants to steal it

A useless product, it never worked, except when I put the battery in and heard the siren (on the street with all the noise, I doubt anyone could hear it...)

Small in size with a relatively strong (alternating) siren sound. Its main problem is its sensitivity. It requires intense vibration to activate.

Edit:
After using it for about a month (having to activate it 5-6 times for durations less than 10 minutes), the battery drained.

For the price, it's good. It does the job for a bike, but it shakes and scares the other person riding with you. I don't know yet how long the battery lasts because I read that it gets consumed relatively quickly. They sell it a bit expensive compared to the fact that you can find it for 5 euros from China. You just need to be patient for a month. It depends on how much you really want to get it.