This four-season mountain sleeping bag offers great value for its feature set. It's designed for mountain enthusiasts and built to offer protection in the mid mountains. Expert Series The SUMMITER is warm and comfortable thanks to the excellent warmth-to-weight ratio of the down, which traps the air heated by the body. After being compressed, the down regains its loft. The internal insulated shoulder collar seals heat and stop it migrating towards the head. The mummy fit is close to the body and snug, reducing the amount of air to heat up, and thus keeping you warm more easily. The shell is in a soft, water-repellent polyester fabric. Its ripstop weave is lightweight and resistant to abrasion and tearing. It thus stops down poking through, while remaining packable and easy to carry. A compression sack protects your bag from dirt and water, and also frees up storage space in your pack. This sack also serves as a pillow, once turned inside-out and filled with 1-2 bits of apparel. Its soft brushed microfleece is warm and comfortable against the skin.