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Western Mountaineering says:
At just 14 ounces, this bag is setting a new standard as the lightest weight hooded sleeping bag in the world with baffle chamber construction. We have combined the finest materials and feature set including the worlds finest goose down, a balanced 10-denier fabric, a half-length #3 coil zipper with insulated draft tube, and an insulated top collar.
Compressing down to almost the size of a standard water bottle, the Flylite is a perfect choice for fast packers, adventure racing enthusiasts, bikepackers or anyone that is looking for the lightest possible bag that they can still get a full night’s sleep in.
Rating & Materials
* Western Mountaineering state: 'We independently verify own temperature ratings through our own testing, customer feedback and design knowledge. Most of the items in our catalog we have been making for years, which means we have lots of prior knowledge from everyday consumers on what ratings are accurate. We have also EN tested our bags. In every case the EN rating is lower than our posted rating. This means our ratings are more conservative. We do this to ensure that almost everyone will be happy in our bags at the temperature we publish.'