Whether you are after trophy elk or whiskey sippin', Park Series bags are ideal for serious hunters or those hunting for a sleeping bag with tons of room. With packable weights, highly compressible construction and our ultra-warm Insotect FlowTM construction, Park series down bags are Big Agnes System bags geared for those who want a little extra girth but might want to carry their bag on their back from time to time. Park bags use Big Agnes' full pad sleeve design and require a 25" wide pad. Flow Construction eliminates lateral and vertical down shifting by using vertical chambers with Flow Gates to regulate fill positioning and density. Strategically placed Flow Gates minimize vertical down shifting while vertical chambers minimize lateral shifting. With continuous vertical Flow chambers in place of traditional side seams, Flow bags eliminate potential cold spots which can occur with side seams. Vertical baffles now flow with your body for more rapid and uniform body heat distribution. Shell: Down proof, nylon micro-fiber rip-stop. WR surface treatment to repel water. Lining: Soft, breathable down proof nylon with stain resistant finish. Pad sleeve: Nylon rip-stop. WR surface treatment to repel water.