This vest gives you more bang for your insulation buck by maintaining 98% of its warmth, even when wet.Just think how far your dollar will go when you invest (pun intended) in Patagonia's Nano Puff Vest. Enjoying the great outdoors likely means you're going to face unpredictable weather at some point. Keeping your core warm no matter how wet the conditions get is vital to having a good time. It could even be the difference between being miserable and having to cut your ascent of Mount Kilimanjaro (the tallest free-standing mountain in the world) short or continuing on to the summit. The insulation is highly compressible, breathable, as soft as down and still keeps you warm if it gets wet. More than half of its content is recycled. Add that to an outer shell and lining that are made from 100% recycled polyester ripstop with a DWR (durable water repellent) finish and you have a vest that's warm, windproof, water-resistant and less damaging to the environment. 100% polyester (60g) insulation. Imported.PrimaLoft Gold Insulation EcoThis synthetic insulation offers an excellent warmth-to-weight ratio and maintains 98% thermal efficiency when wet, all while using 55% post-consumer recycled fibers. PrimaLoft uses a proprietary microfiber structure that helps retain your body heat and thereby helps you conserve the energy your body usually uses to stay warm. So how does this insulation remain warm when it's wet Using fibers that are just a fraction of the diameter of a human hair, PrimaLoft forms a tight collection of air pockets that trap heat from your body and keep the cold out. Unlike insulation that loses these air pockets when it gets wet, PrimaLoft's ultra-fine fibers create a tight surface tension that won't allow water to pass through and have unique, permanent finishes that repel water and keep the insulation drier, even if water is forced into the insulation. These fibers also mimic the softness and compressibility of goose down and are breathable so moisture vapor is transported through them and away from your skin.Resists Wind & WaterThe Nano Puff Vest features a 22-denier shell and lining of lightweight (1.4oz.) 100% recycled polyester ripstop that is water-resistant, windproof and warm. A durable water repellent (DWR) finish is applied to shed light rain and snow and decrease drying time, yet still allow the fabric to breathe for exceptional comfort