I had four and one fell off. It definitely shows that you have friends that care whether they actually work or not. I have to give credit to whoever came up with this as it was very clever.
The cool thing is that at certain times the wife and I can actually hear them. They are all mounted low at the rear of the bike.
It’s best to put your trust in the Lord, use the brain he gave you, be careful and stay alert.
I have one, a buddy bought it for me when I was at the dealership buying my first bike. I have it on the bottom of the down tube and I swear I can hear it ring sometimes. Anybody else hear theirs?