This REI Zephyr +15 backpacking bag's light, compressible insulation and unique construction work together to maximize warmth when the temperature dips. FILL. Polyester fiberfill. TEMPERATURE RATING (F). 15 degrees (F)

• Unique Z-Baffle construction maximizes loft, ensures consistent insulation coverage and prevents convective heat loss
• New, exclusive REI® insulation uses the best blend of polyester fibers for a lighter, more compressible bag
• Stuff extra clothes into the hood's pocket to create a pillow; no need for a pillow to take up valuable space in your backpack
• Exterior chest pocket is great for stowing small necessities like your watch or lip balm, alleviating middle-of-the-night fumbling
• Pad loops provide attachment points to keep your sleeping bag and pad together to avoid rolling off onto the cold ground (straps sold separately)
• Differentiated drawcords allow quick identification, even in the dark so neck or hood adjustments are a cinch!
• Full-length zipper, contoured hood, insulated muffler, roomy foot box and full-length draft tube keep heat in, cold out
• Mummy bag design is thermally efficient, yet wide enough from hip to knee that you have room to move for sleeping comfort
• Compression stuff sack and cotton storage sack included