Welcome to Over50sForum! The site for people over 50 to chat, make friends, discuss, share, and generally be part of something that's fun and friendly :)
Yes i used one for back problems it did work had 3 settings and a few levels in each. Used it both on the move and at home, certainly helped me, gave relief for a while.
I use to put it on my shoulder for about half an hour at a time before I did my exercises to try and get some movement back in my shoulder and arm. It doesn't cure the pain just helps relieve it for a while.