The Helium Down Vest is that durable, lightweight layer you're reaching for on that shoulder season hike around the foothills. You'll want warmth, but freedom of movement, and that's what the Helium offers. Pertex Quantum with Diamond Fuse Technology protects 800+ down fill with an outstandingly durable and abrasion-resistant shell. But, it's still lightweight and packable so you'll have no trouble with a bulky layer.