I had two, and honestly it didn't do much for pain but cranking it up would move an entire limb, and fast.

Perhaps mine had some beefed up voltage.

I did find that if I cranked it up too high, two days later, I hurt a ton....so tell Alan not to crank it up like that...my muscles would spasm.

Electrical stim has done zip for me in terms of pain control....it does work for some folks, but the darn thing buzzing like that was as obnoxious as pain...and did nothing to really relieve it. I had two TENS units over the years....one was prehistoric...that was a late 80's model they gave me after my car accident.

Keep in mind, I have a plethora of injuries, not to mention an interesting assortment of disease, so, I hate to discourage any one from trying something that may work for them.

Same rule applies, give it a try if it can't hurt.