I purchased this device a few months ago because I needed something that would get right down into the tension of my muscles which tenses up ever so often just because of daily life and 'neglect' on muscle care and sometimes painful movement. I use it every other day and am very pleased with results to date. The tension in those muscles are easing and I am feeling a lot more agile in my movements. I also like that it can be charged up using a usb connection. I'm writing this review now because I purchased another device, battery operated from another merchant, before I saw this one and used it recently just to see how it will work and was very disappointed as it actually 'bit' into my flesh leaving lesions. The mechanics of the Caremax Tens machine is certainly optimal. This device is my go-to relief when feeling aches in my body. The only issue I have is that I struggle to set the timing even though I follow instructions, hence 4 stars. Otherwise I would've given it five stars.