Sleek, light and surprisingly warm, the Nano Puff Pullover's modus operandi is one of versatility. It's an insulated pullover in spring squalls, a sleek micro-belay parka on chilly rock routes and a thermal midlayer all in one. The Nano blocks wind, sheds snow and traps heat - even when wet - with the best available synthetic insulation: PrimaLoft ONE (60-g) is incredibly warm, low-bulk, compressible and hydrophobic. We've improved the fit with more shaping through the torso and waist, and refined the deep-venting half-zip with a soft, wicking interior storm flap and zipper garage. We also resized the classic Nano Puff "brick" quilt pattern, added horizontal quilt lines on the side panels, and used a burly thread for enhanced durability. The 100% recycled polyester ripstop shell glides effortlessly as an outer or midlayer, and it all packs down to practically nothing and stuffs into a single chest pocket that has a carabiner clip-in loop. Elasticized cuffs and hem seal out wind and trap warmth.