What Our Gearhead(R) Experts Are Saying:"I brought this on a cold-weather mountaineering trip and was honestly surprised by how little it weighed, given how warm I stayed overnight. The tapered mummy shape kept heat close without feeling restrictive, even after a long day of climbing."High alpine nights demand serious warmth without the dead weight, and the Neutrino Sleeping Bag: 10F Down delivers exactly that balance for trekking and mountaineering trips where every ounce in the pack matters. 800 fill power goose down packs impressive heat retention into a remarkably light build, so cold camps at elevation stop feeling like something to dread. L. O. F. T 3D baffle technology keeps down evenly distributed through the night, eliminating the cold spots that plague lesser bags, while longitudinal chest baffles add extra thermal efficiency right where it counts. The anatomically fitted hood cinches down for maximum heat retention, and a tapered mummy shape keeps things efficient without sacrificing room to move through the shoulders and hips.