This Filson Down Liner Jacket pulls double duty as a warm stand-alone jacket or a zip-in liner for select Filson raincoats. The midweight, synthetic shell fabric is water-resistant, downproof, and rugged enough for demanding field use. It’s insulated with goose down, nature’s warmest and lightest insulation. The rib-knit collar and cuffs feature a high wool content for durability and warmth, even if they get wet. This versatile layer zips into compatible Filson jackets and secures at the neck cuffs with buttons