This device does just what it says it does, namely relieve pain through a combination of heat and massage. It works for several hours on a charge, and will run continuously for several hours on that charge. You can change the vibration and heat settings and also add a heating pad or even a cooling pack and use it without heat. I am slowly recovering from a shoulder fracture and this provides some much needed relief from pain due to muscle spasm. I have two complaints: 1) you cannot see the box to turn it on or change settings, and 2) it will not work while charging, and so, you must take a break for the time it takes to recharge it before applying it again. I don't have any kind of "fast charger". So the best solution, IMHO is to purchase two. If it is not charged up at bedtime, I wear it while charging and then can turn it on when I wake up in pain.