The REI Big Cat 0 is a relatively low-cost bag that features the attributes of down fill--efficient insulating properties with relatively light weight. In addition, the bag is specifically cut for a more roomy fit, with a wide girth; this is accomplished with minimal bag weight gain. The pesto-colored Big Cat uses box baffle construction to distribute the insulation throughout the bag while allowing proper loft. The bag uses 600-fill power goose down; this provides good insulation (when dry) with moderate weight and packing size. The bag does not use a fully articulated jacket-type hood as with some bags, but differentiated drawcords allow you to cinch up the hood and neck for warmth. There are dual insulated neck mufflers for added warmth. Rather uniquely, the bag uses two zippers; there is a long side zipper, as well as a short side zipper for venting and arm access. The long side (anti-snag) zipper is full-length and additionally runs along the bottom of the bag and allows you to open the bag fully to create a comforter. A draft tube runs the length of the zipper. A nylon stuff sack and larger cotton storage sack are included. The Big Cat comes in regular and long sizes; both sizes are also available in +20 degree models. The Big Cat 0 is a good choice for three-season and moderate winter camping; its large cut makes it comfortable while not incurring a large weight penalty for the added comfort.