We’ve had several threads about those. I’m kind of surprised nobody has jumped in already to share their opinion. I think it can be a good way to deliver the click in a really not-ideal acoustic situation. Beyond that, I’m not sure how much better they are than a regular metronome/click.
I can see this causing problems if only the drummer wears one and the band starts to drift - kind of like what happens when you find yourself listening to two songs at the same time. Is it easy to turn on/off while playing?
Anyway, found out they make a similar device for tuning instruments as well.
Do they make something to help singers stay in key?
I was offered a “like new” one for half the price. I tried it for a few minutes and didn’t like it. It seemed difficult to feel anything while moving as I do when I play. Plus I thought I have enough devices that need to be charged. The quality of the unit seemed to be pretty good though.