Spend a night with Big Agnes and youll look forward to sleeping in the backcountry. The mens Big Agnes Lost Ranger 15 Degree Sleeping Bag System is different than the traditional sleeping bag on top of a sleeping pad. Instead, Big Agnes unites the two. The pad not included slides into an integrated sleeve on the bottom of the bag, and the top two-thirds of the bag is insulated in the traditional style. When insulation material is compressed under your body, it loses most of its ability to insulate. Big A. eliminates the unnecessary bottom insulation and replace it with a sleeve to accommodate the pad which provides the insulation. This design provides a secure foundation and keeps you on the pad all night. With 650 fill goose down insulation, this rectangular shape design offers more room in foot box and shoulders.