Big Agnes Sidewinder SL 20°

The Sidewinder SL 20° is the lighter, men's-specific version in the Sidewinder line, carrying the same patent-pending design for side sleepers. It combines 650-fill hydrophobic DownTek down with body-mapped FireLine ECO synthetic insulation at the hips and feet — the areas where down loses loft fastest under body compression. An ambidextrous center zipper and jacket-style hood cut allow free movement and rolling over without the bag twisting around the body. The -1°C comfort / -7°C limit rating is EN ISO 23537 tested, giving a more directly comparable figure than a manufacturer-only rating. At 1020 g and roughly 145.7 g per degree, it is considerably more efficient than the synthetic Camp-line bags, with down doing most of the thermal work at a lower weight. RDS (responsible down) and bluesign certification, plus PFC-free treatment, place it among the more sustainable down options. It ships without a compression or storage sack, an added cost to factor in. It suits side-sleeping hikers looking to trim pack weight on multi-day 3-season treks without giving up sleep-position comfort.