The waffle stitch traps dry air in generous micro-pockets against your skin, creating a buffer that regulates your core comfort. Comfy and lightweight, this relaxed-fit long sleeve crew looks great from the garden to the summit hut. Quite possibly the world's lightest, warmest fabric. 80% Helle Rambouillet Merino wool plus 20% Polyester to help maintain the waffle shape. Great layer cool weather wear and travel - the breathability of the waffle construction makes this a very versatile addition to your all season essentials.