Big Agnes

Sidewinder SL Sleeping Bag: 20F Down

What Our Gearhead® Experts Are Saying:

"I'm a side sleeper, and this is hands-down the most comfortable bag I've used. The body-mapped insulation makes a huge difference at the hips and knees, and I love how the bag moves with me when I roll over. The 20°F rating is perfect for spring and fall trips."

We’ve tossed and turned our way through plenty of mummy bags, but the Sidewinder 20°F Sleeping Bag finally gives side sleepers a reason to sleep well in the backcountry. Designed for the natural way most of us sleep, it features a sculpted shape that moves with us as we roll from side to side, plus extra room at the elbows and knees where we need it most. Whether we're curling up on a cool fall night or shifting positions mid-sleep, this bag keeps the warmth close and the pressure points off.

Insulated with a hybrid of water-repellent 650-fill DownTek™ and body-mapped synthetic insulation, the Sidewinder 20°F targets warmth where we need it—around the hips, shoulders, and knees—while staying compressible enough to pack easily. The recycled polyester shell features a PFAS-free water-repellent treatment to block moisture and condensation, while the close-fitting jacket-style hood seals in heat without restricting movement. Lightweight, warm, and tuned for real comfort, it’s built for the way we actually sleep outdoors.