Great for lumbar or cervical in TENS, these electrodes have the advantage of covering a larger area than small square and we gain in profit. Some do not seem to have understood the interest of a gel: it keeps the electrode "hydrated" and thus delay aging of the combined effects of drying and accumulations dust / hair / dead cells and fat from the skin. The maintenance gel electrodes over time and prevents too much hair / dust etc .. accumulate thereby decreasing their effectiveness. Personally I use the Compex gel that can be found in the 8/9 250ml and is perfect.