The Traverse transitions easily into warmer weather with a full-length left-side zipper, a half-length right-side zipper, and a foot box zipper. The Free-flow zipper system provides unparalleled ventilation or allows the Traverse to be opened completely flat like a comforter. In colder weather, the unique WaveLoft construction allows the Thermolite insulation to expand out into air-trapping curves for maximum warmth.