Nylon 45-degree Fahrenheit (7-degree Celsius) ultralight down sleeping bag for warm weather backpacking, bike packing, and touring High-loft 850+ fill power down insulation (Responsible Down Standard certified) with a non-PFC Ultra-Dry down treatment to improve reaction to moisture, retaining loft and performance Ultralight 10D shell with PFC-free DWR keeps the hood and footbox highly water resistant; breathable 10D nylon liner provides all-night comfort Contoured mummy shape provides adequate room for a natural sleeping position; YKK #5 zippers provide reliable, snag-free operation Baffle construction is sewn through for lighter weight; Sea to Summit Guarantee is offered for the Lifetime of this product The Sea to Summit Spark 45-Degree Ultralight Down Sleeping Bag is a technical down bag, engineered for warmth at the lightest weight and smallest compressed size. Ideal for backpacking, bike packing, and touring, the mummy style keeps the cold out and the warmth in. High-loft, 850+ fill power down insulation (Responsible Down Standard certified) is treated with proprietary non-PFC Ultra-Dry Down treatment to improve reaction to moisture and retain loft and performance in rugged conditions. The contoured mummy shape provides adequate room for a natural sleeping position and features sewn-through construction for lighter weight. The ultralight 10D nylon shell and liner fabric is treated with PFC-free DWR and offers cutting-edge packability and warmth. A weight-saving YKK #5 zipper is one-third length, on the left side and operates snag-free. The Sea to Summit Spark 45-Degree Ultralight Down Sleeping Bag is available in two sizes: Regular (max user height of six feet) and Long (max user height of six feet six inches). It includes an Ultra-Sil compression sack and storage cube. Sea to Summit products are guaranteed against defects in materials or workmanship for the lifetime of the product.