The two main differences between the Bobcat 45ºF and Bobcat 55ºF are the recommended temperature and type of fill. The Bobcat 45ºF is a down trail quilt recommended for use at temperatures of 45ºF and above, while the Bobcat 55ºF is a synthetic trail quilt recommended for use at temperatures of 55ºF and above. The Bobcat 45º is made from Downtek™ Insulation, a responsibly sourced, water-repellant down. The Bobcat 55ºF quilt is made from 100% recycled synthetic fill - the equivalent of reusing 15 plastic water bottles. Because of its lightweight down fill, the Bobcat 45ºF does weigh 4 oz less than our Bobcat synthetic trail quilt and packs down smaller. the quilts are 20 oz and 24 oz respectively.