FIRSTGEAR® Gen4 Heated Pant Liner warms you in seconds, yet was designed to feel like part of you - form-fitting, for optimum heat transfer to the body. Durable, hand washable, and extremely lightweight, this version uses Gelanots, a breathable and waterproof stretch fabric in the front to block the wind, as well as a wicking effect when wearing jeans or other porous pants. The new "soft heat" heating panels have soft and flexible carbon shape for maximum heat transfer. Materials contribute to allowing full range of movement for any activity and fitting easily under your outer garments. Heated zones cover thigh, knee and upper butt with 48-Watts of heat. All this efficiency means less insulation and power is required to deliver and retain the desired heat. Only the best goes into the Heated Pants Liners: High-tech, wicking, stretch fabric construction with different cuts for men and women, YKK zippers, carbon "soft heat" heating element, connectors and wires rated to -40 F for durability and longevity.