The Fireside Mummy by Chinook® features 350 grams of 90/10 grey duck down, 575+ fill power insulation giving this bag a great weight to temperature ratio. Chinook rates the Fireside Mummy at 2°C (36°F) providing plenty of warmth on those late spring to early fall hikes. The bag has an outer shell made of honeycomb & diamond rip-stop nylon which will provide durability and promote long use. Also for durability and long use, this sleeping bag uses a 2-way #5 YKK zipper. The lining is made from polyester to reduce weight and increase compactibility.