I sprained a muscle in my back a week ago. Went to the doctor a few days later when the pain did not subside. Doctor put me on anti-inflammatory and a muscle relaxant. Took those for 5 days and the pain was still unbearable. The doctor had suggested I try a TENS machine. I ordered this one on 鶹 (best value for the price, plus I liked the wireless aspect). It arrived early this afternoon. Used it immediately (after charging it as suggested) for 2 twenty-minute sessions. Then I laid down for a nap after supper and used it for another 20 minutes. When I woke up from my nap (about 2 hours later) I used it for another 20 minutes. For the first time in a week I was able to get out of bed without screaming with pain. The pain is not completely gone but it's gone from a 10 (excruciating pain) to maybe a 4 or 5 -- and this in less than 8 hours since it arrived in the mail. I will use it again when I go to bed and first thing in the morning. But must say so far, I've definitely gotten my money's worth on this product. I am now sitting without any pain/spasms which I haven't been able to do for a week. I absolutely recommend this. Also I had to call the company with a question about extra pads, and the customer support was super helpful and friendly. Definitely a 5-star product and 5-star service. Can't say anything about the longevity of the product since I only received it today, but since my pain is more than 50% gone at the moment, I'm super happy with it.