Easy to use after reading the instructions IMPERATIVE. Very convenient to put nothing, the water on the back and on the electrodes suffice. The intensity between 1 & 10 we do not feel anything. After 10 to 20, you really feel the effect and there is a relief in the moment and even after. I use it once a day and have less back pain, but it is not a miracle product, it's just a tool that promotes mitigation backache, not the complete disappearance.