The four new lightweight Couloir down sleeping bags have a Technical Mummy profile with a Toray nylon Taffeta shell to ensure performance. This is enhanced by the double zip baffle and the new oversize contoured thermocollar (except Couloir 250) that creates a snug fit over the shoulders to eliminate heat loss through the bellows effect. Hood and baffle drawcords are repositioned for ease of use from within the bag and all couloir sleeping bags feature a centre zip for easy access – a feature appreciated when in the confines of a small lightweight tent.