Been going to PT for four weeks, last thing they do is put me on electro shock for 15 minutes. Last week, they told me I could buy a smaller version. Started doing research and asking around, was kinda shocked how many people knew what I was talking about when I said "TENS unit" and how much they loved their's. Got this one on Amazon for $28, has 4 inputs (can do 8 pads), 15 or 16 modes, and had 4.3 rating with nearly 12,000 reviews. Took it with me to PT today, they showed me which settings would be best for my situation and walked me through how to use it (instructions suck!).