Cocoon Merino Wool Mummy Liner

The Cocoon Merino Wool Mummy Liner is a 495 g sleeping bag liner made entirely from merino wool and cut to a mummy shape to match a mummy-style bag rather than a rectangular one. Used inside an existing bag it adds roughly 7°C of warmth, enough to stretch a three-season bag into colder nights or add a safety margin on a bag rated close to the conditions you expect — it won't turn a summer quilt into a winter bag on its own. Merino's main advantage over synthetic or silk liners is odour resistance: it holds up over several days of use on a multi-day trip without smelling the way synthetic fabric does, useful when a full wash isn't an option on the trail. At 495 g it's heavier than a silk liner and takes up more room in your pack, so weigh that against how much extra warmth and odour control the trip actually needs. It also works on its own as a warm-weather sleeping bag or a sheet for huts and hostels where a full bag would be overkill.