I purchased this sleeping bag with the intent of taking it into very cold areas. I like to sleep without many layers on, but get cold easily. I am 5'11" and went with the long bag because i wanted somewhat of a foot box to put clothes, water bottles, boot liners, ect. I took this bag with me to Argentina to hike Mt Aconcagua, which is the 2nd highest of the world 7 summits, standing at 22,851ft. I used the bag for 17 days on the mountain, utilizing a silk liner inside the bag to help keep the bag cleaner. This bag was slightly heavy, but it is extremely warm. Some nights the temperature dropped WAY below zero, and I was happy sleeping in shorts at 20,000 ft. The bag also stayed very dry, water beaded right off it and I never had to worry about it getting wet and drying it off. Very durable, warm, waterproof, comfortable, well made and designed!