Every backpacker needs a good compression sack for the sleeping bag, a small bag to organize random essentials, and a dry sack to keep insulated layers dry. Good thing you found the Outdoor Research Dry Drown Backpackers Kit, because it includes all three. Stash your down insulated sleeping bag inside the Airpurge Dry Compression 10L Sack, and suddenly it takes up less space in your pack and it's protected from warmth sapping moisture. Your insulated midlayer can slide into the Ultralight Dry 10L Sack and other small essentials can stay wrangled inside the Mesh Ditty Sack. To underestimate the effect of moisture on your down insulation would be disastrous.