Features nylon Big Agnes Lost Ranger 15° Sleeping Bags (650 Down fill), Long Left Zipper Description Product Description Updated for 2015, the Classic Down series offer warmth, compressibility and the Big Agnes System bag design. Classic Series bags combine a roomier contour shape with a narrower pad sleeve to provide an overall more comfortable and cozier sleeping experience than ever before. Big Agnes also redesigned the bag to be taller across the top so you can roll over more freely. The ergonomic hood gives you more range of motion so that you can move unrestricted while staying hooded. FlowTM Construction: Insotect FlowTM is a flow-optimized insulation system that delivers uniform heat distribution and natural body contouring through its revolutionary baffle design. 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.