Above treeline, where temperatures are cold and exhaustion lies just below the surface, every ounce counts. So, it's a good thing we stashed the Rab Endurance Down Mittens in our pack for instant warmth and emergency use. Packed with 650-fill down-plus synthetic Stratus insulation in key areas for better performance in damp conditions-these mittens ensure warmth in extreme environments while weighing less than 9 ounces. Pertex Endurance Pro laminates the mitts in a hydrophobic finish to protect our hands against heat-zapping moisture, and they're also reinforced in the palm and fingers for better durability and grip. Overall, Rab made these mitts for light use in harsh conditions or for emergency use when alpine climbing or winter trekking in seriously cold temperatures.