Well, Mel, I just wrote a long reply pontificating about all my knowledge about TENS, but it somehow got erased. You are so lucky. The short version is: TENS can cause a burn under the electrode if improperly used. Since Alan has a history of poor wound healing on his feet, don't use this unless you get a referral to a physical therapist who can evaluate him and instruct in the proper use. I am worried about his feet, due to his history of skin problems and the fact that he might not be able to feel the TENS burning him. A new wound could be devastating for him.