The Crescent Lake series sleeping bags from ALPS Mountaineering are made with Techloft insulation. Techloft Insulation consists of multi hole staple length micro denier fibers that have a siliconized finish for maximum insulation, loft, and compactness. The Crescent Lake uses a 2 layer offset construction, sometimes called a bag within a bag. The contoured hood and mummy shape helps seal up your warmth and keep you warmer. The Crescent Lake is a great backpacking sleeping bag to take along on your hikes that won't take up all the space in your pack.