Building on a reputation for weatherproofing and wearability, the 509 Forge Insulated Jacket enhances one of our most respected styles with 100 grams of Thinsulate insulation. Fully seam-sealed 5TECH 150D waterproof/breathable fabric stops any storm in its tracks, while details like water-resistant zips and gaiters at the wrists and waist lock in the warmth. The relaxed fit gives you room to add 509 mid and base layers underneath on the coldest days.