Pretty good
I bought this because I have asthma and I wanted the extra support when going back to work. It seemed to work well, it was way too long, so I used a binder clip to move it closer to the middle of my chest. I didn't really notice a difference when wearing it, but it must work because when I forgot it at home the one day, it was much harder to breathe with my mask all day and I really struggled. I do recommend this, just use a binder clip to shorten the length of the strap so it sits in the middle of your chest. The battery life is pretty great, and it lasts more than an entire work day.
Rating: 5 stars