12V heated vest liner is a very lightweight, easy to stow package. While not quite as warm as the full jacket liner, it's perfect to throw on under your leather or textile jacket for early morning starts, or cool evening rides. Designed to be worn close to the body, under your outer jacket and over a thin polyester base layer. Droptail back for improved coverage while riding. Mini Ripstop nylon shell. Five Microwire™ heating zones: collar (1), chest (2), back (2). YKK® zipper. Pre-Wired connector for pant liners. All Gerbing installations require a Battery Harness and Temperature Controller for operation (sold separately).. We recommend the use of a temperature controller with this product. Failure to do so may cause discomfort & burns..