The Mountain Hardwear Rook 15 Degree Down Sleeping Bag offers a happy medium that's perfect for shoulder season backpacking trips. Filled with a lofty dose of down insulation, you'll barely notice its weight in your pack, and it offers heat-trapping warmth that stuffs down nicely on longer trips. Treated with a durable water repellent, the down is protected from light precipitation while you're setting up camp, or chance spills from your reservoir. A traditional mummy shape delivers efficient heat retention on chilly fall nights, while the two-way zip lets you welcome in some cool air when the morning sun hits your tent.