Looking for a warm windshell, an insulating mid layer, or a backup jacket for rest breaks? The Helium is a classic, no-frills down jacket – and incredibly versatile. The jacket is very light, super warm and packs down small. The Stormlock outer fabric shuts out the cold wind, thereby increasing the insulation performance. The jacket comes with a practical stuff sack, so you can stash it in your pack for when you need a bit of extra warmth.