The Marmot Trestles 15 Degree is one of the best three season backpacking mummy sleeping bag values on the market. Bring the all-purpose Trestles 15° Sleeping Bag - Long, built to perform in cold and damp conditions as you're backpacking, trekking, mountaineering, and more. SpiraFil™ high-loft insulation will keep you warm even when things get wet. After a long day of exploring, zip up the full-length two-way zipper, pull on the 3D hood, and give your feet a rest in the roomy 3D footbox. Its wave-construction top and blanket-construction bottom provide an unbeatable combo of maximum loft, warmth, and comfort where you need it. If the interior gets too toasty, use the fold-down secondary zipper to get some air. Tuck small items into the stash pocket.