I am always hesitant to endorse a product. However, I do post on Gransnet about other stuff, so am responding genuinely.
I have arthritis that I usually manage with anti-inflammatories. Sometimes I get tendonitis (an inflammation of a tendon). I find the Paingone pen very good in those circumstances. It's easy to carry about. I think everyone has to work out the best circumstances for them to use it. I find it very specific to the area I use it, so it wouldn't help with general joint inflammation.
It doesn't completely remove the pain, and of course I am aware that I need to rest the tendon, but on some occasions hen I need to get through something, it has been very useful.
It is a simple way of carrying about a TENS machine, but targets small areas. I would use it by giving bursts along the tendon.
Hope this helps.