Our 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. Down is the soft plumage that lies beneath waterfowl’s tougher exterior feathers. These soft, fluffy clusters provides geese with the insulation needed for survival in frigid temperatures and wet, icy conditions. Goose down is widely regarded as the warmest insulation available. Ours is responsibly sourced–we partner with suppliers in voluntarily compliance with the Responsible Down Standard (RDS).