Form fitting with Spandex Performance fabric for optimum heat transfer to your body Dual zone heating Zipper pouch included Spandex fabric allows full range of movement Fits easily under your outer garments Liner is designed to be plugged into a DC power source or battery pack and built to be temperature neutral, so that you can wear your liner all day and not have to change clothing when you need heat Portable Heat Troller Dual 382-136