An extremely breathable insulation. Mid/lightweight with durable F.Cloth exterior, super breathable Alpha 60 insulation in the middle and a soft and dry nylon-core merino on the inside. Alpha is a US mil-spec insulation optimized for extreme breathability to create a nice amount of warmth without overheating. Because Alpha is optimized to be a non-migrating insulation it can be paired with much more breathable face and lining fabrics than most insulations (which require very tight faces to keep the insulation materials from leaking out.)
The nylon-core merino interior keeps things soft and dry with all of the natural performance of merino. On the outside is the the rugged but breathable F.Cloth with an FO Zelan R3 DWR treatment for quick drying and handling light rain and snow. This combination traps a nice amount of warmth but begins to dump heat before things get too hot. At the 60 gsm Alpha weight this makes for great indoor/outdoor use, and a versatile layering piece.