The First Ascent down range features the highest quality down to provide superior insulation. Down's fill-power rating is an indicator of each garment's warmth-to-weight ratio and compressibility, both features which give down its ability to retain warmth and provide unrivalled comfort. First Ascent down garments feature a fill-power rating of 600 to 800 and are insulated with a high down-to-feather ratio, giving each garment its high loft and exceptional insulation benefits.