The Crescent Lake series sleeping bags 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.