Big Agnes Sidewinder 20 Sleeping Bag

Built for comfort, this Big Agnes sleeping bag is made specifically for people who sleep on their sides. It combines down and synthetic insulation for just-right warmth. And it compresses down small.

Temperature ratings are intended as a guideline to help you compare products, rather than a guarantee of warmth, since many different factors contribute to your comfort while you sleep. Backpacking bags are typically rated for temperature according to an independent testing protocol—currently International Organization for Standardization (ISO) 23537, though some older items followed European Norm (EN) 13537. Testing is based on a person wearing one base layer and a pair of socks, sleeping on an insulated surface with a minimum R-value of 5.38.

Each bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.

• Designed for the over 60% of people who sleep on their sides
• The 2nd generation of patented Sidewinder side sleeper technology ensures warmth, comfort and ease of use in any position you settle into
• The technical fit is patterned to move with you as you roll from one side to the other
• Down fill with a water-repellent finish throughout the bag provides lofty warmth
• Body-mapped FireLine™ Eco synthetic insulation
• Strategically placed synthetic insulation provides padding and pressure relief at the knees, hips and shoulders
• 100% postconsumer recycled polyester features low-denier fibers that are tightly woven and provide high loft, compressibility, high warmth-to-weight ratio and durability
• Optimized profile and thermally efficient footbox are patterned to mimic the body position while lying on your side
• Close-fitting, jacket-style hood keeps insulation close to the body without sacrificing mobility
• Keep your pillow (not included) in place with the Pillow Barn made of stretch mesh material with interior access from either side for easy adjustment
• Smooth, quick zip with an antisnag locking zipper with a no-draft zipper garage and a long, ambidextrous zipper
• Easily adjust the hood without unzipping using low-profile internal cordlock access
• Seal out drafts by cinching the insulated tube along the upper hood opening
• Storage sack and stuff sack included
• Compressed dimensions: Short: 8 x 10 in.; Regular: 9 x 10 in.; Long: 9.5 x 11 in.
• U.S. Patent 11957260 B2