The Men's Summit Ventrix Midlayer from TNF is an insulating layer designed to keep you warm while moving in the mountains. The Ventrix material stretches and breathes very naturally, so you can go from a hot and sweaty mess to a stationary cold mess without compromising the fit or insulation of this midlayer. Just keep it on all day and stay warm. The midlayer is comprised of 60 g of Ventrix™ stretch synthetic insulation in the body and 40 g in the sleeves to keep your core warm and your arms free to move. There are wrist gaiters with thumb holes to help layer this piece without getting the sleeves bunched up. Don't forget the zippered dual side-entry pocket to hold all of your important things (whatever those might be). If you're looking for a midlayer that can keep you warm regardless of the pace, while dumping heat better than the rest, look to this hoodless synthetic puffy.