The Arc'teryx Men's Proton LT Hoody is a highly versatile lightweight and insulated layer. It effectively walks a tightrope of being warm being wind-resistant being breathable and being highly durable all at the same time! The jacket's face fabric is air-permeable Fortius Air 20s nylon fabric with a touch of elastane that allows it to stretch and move with you during aerobic activities. Gusseted underarms and articulated elbows further promote unhindered movement. Though the fabric is lightweight and breathable it also delivers a high degree of abrasion-resistance. It isn't truly waterproof and seams aren't taped but a DWR finish does help the fabric repel moisture. Coreloft Compact 80 insulation in the body of the jacket provides warmth without adding excessive bulk and its synthetic properties allow it to insulate even when wet. Even the helmet-compatible hood has a thin layer of insulation to help bolster warmth. Other features include A full-length front zipper with a protective rear flap to keep out wind stretch-knit cuffs two insulated hand pockets and a zippered chest pocket. Available in your choice of size and color options the Arc'teryx Men's Proton LT Hoody has a trim fit that is best worn over baselayers or low-profile midlayers. This cut does allow you to comfortably wear a hardshell over top of it.