Filson Field Pack in Army. Filson Field Pack in Army. Water-resistant nylon twill fabric exterior and lining. Zip top closure. Adjustable shoulder straps. Exterior slit and zip pockets. Interior zip pocket. Measures approx 13 W x 18.5 H x 7 D. FILS-UY43. 20019933. Built on the values of honesty, quality, and durability, Filson has been outfitting the rugged since the Gold Rush of 1897. Remaining dedicated to founder C.C. Filsons vision, each product is made from outstanding materials, capable of withstanding almost any condition.