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 that provide unparalleled ventilation or allow 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. Whatever the season, the wider mummy cut of the Traverse gives you room to move, no matter what position you sleep in.