In reply to tony:
I reviewed this one a couple of years ago and was relatively sceptical, although it's worth noting that the model in question was quite compact - hence maybe not quite so effective.
Having re-read the review, I was taken by the following lines from within the summary:
"I think the key to whether or not the Addsfit Portable Massage Gun is a success largely depends on whether or not it actively encourages you to use it"
It's quite telling that in the two years since I wrote the review, I've barely used it...
https://www.ukclimbing.com/gear/climbing/training_aids/addsfit_portable_mas...