Slumberjack Lapland -20 Down Hybrid Mummy Sleeping Bag Dri-Down insulation: Down is treated with a molecular level polymer to create a hydrophobic finish on each individual down plume. This finish allows DriDown to stay dry longer, loft better, and dry faster than untreated down, keeping you warmer in any environment. Hybrid Zone insulation combines Dri-Down & Slumberloft-Pro synthetic insulations. Dual 57" long zippers with two sliders each provide unequaled venting options. External hook & loop tabs combined with dual zippers create "arms out" functionality. "Double-Dri" waterproof panels on the hood & footbox provide additional water resistance.