From the Filson website: "Our Insulated Jac-Shirt is a low-profile field layer that provides heavyweight weather protection. Our Insulated Jac-Shirt is a low-profile field layer that provides heavyweight weather protection. An oil finish Shelter Cloth exterior resists wind, rain and abrasion, while 100g PrimaLoft® Gold insulation retains warmth even when wet. The front snap closure is easy to use with gloves, and side-seam handwarmer pockets are streamlined and snag-free."
