Worth Way More Than Its Weight in Warmth. The men's Burton [ak] Helium Hooded Stretch Insulated Jacket is the midweight layer that should always be on the packing list. You can wear it hiking when it's cool and windy or under your shell to stay warm on a ridge top. It's stretchy enough for an unrestricted feel and breathable enough to wear when you're headed uphill. When you don't need it, it stuffs into its own pocket and easily stows in a small pack.   FEATURES: Slim fit sits close to the body, with room for the garment to move with you Stretchy, breathable, and lightweight 20D nylon and spandex plain weave fabric with a water-repellent coating Thermacore Stretch [40g] insulation offers superior warmth-to-weight performance in a low-bulk design that won't restrict your movement, providing insulation that is designed to move with you and uses bluesign-approved materials that are safe for people and the planet; [ak] DWR coating Attached hood with stretch binding at opening Lightweight low-profile back of hem cinch; Pocket utility loop and media port Packable into a pocket Zippered chest pocket and hand-warmer pockets; Reflective details Products made with bluesign materials are responsibly crafted in processes that minimize impact on people and our planet Lifetime Warranty