Similar but very different. It works on a different frequency than a tens unit. A tens unit blocks pain impulses to the brain where a rebuilder opens up the nerve pathways. Could it be helpful for Fibromyalgia? Possibly Fibro a lot of times is a catch all when doctors do not know what the problem really is.... BTW be very clear I am not a Doctor and none of what I say should be construed as medical advice. For that call Dave (Phillips)... I have talked to him many times and he is a very personable guy.