The Reactor sleeping bag is constructed with a durable polyester shell and a soft polyester liner filled with TechLoft Silver insulation. TechLoft Silver insulation consists of multiple denier staple-length fibers with a siliconized finish for maximum insulation, loft, and compactness. The Reactor uses two-layer off-set construction featuring a contoured hood and mummy shape, which help seal in your warmth. It is a great bag to add to your camping essentials.