I bought this for my husband as a Christmas gift. We both do CrossFit and have aches and pains after most workouts. He tried it out that afternoon m then placed the pads on my lower back and I was in love with this unit. I went directly to the computer and ordered another one. There will be no sharing. We each need our own, lol. As I write this review I have it on my swollen knee. I twisted it last night doing box-jumps. We love this unit! I’ve already recommended it to my 75 year old father. I purchased extra pads, but haven’t had to switch them out yet. The stickiness lasts quite a while. How long? I’m not sure. I’ve personally used mine about 10 times with the original pads. In addition, I like the oval plastic board that comes wit it to stick the pads on and wrap the cord around, when not in use. I use my unit for 20 minutes at a time, but have the option of increasing it to 60 or less.