A simple design makes this product easy to use and effective. The pack is manufactured from a heavy duty supple plastic and has three heat seal divides along its length to allow the pack to be folded easily, so that it can be moulded into the shape of the treatment area. The unit is activated by sqeezing a metal disc that floats in the liquid. The fluid then heats up and you massage the pack until it becomes soft. It remains at a working temperature for about one hour. After this, the pack can be immersed in boiling water and allowed to simmer for about 15 minutes. This re sets the pack and it can then be re-activated at your convienience.