One of the lightest and most versatile traditional 20-degree sleeping bags we’ve tested is the Feathered Friends Hummingbird. It’s only available from the distributor directly, however, the waiting time to get it is 1-4 weeks and you’re unlikely to find it on sale. If you haven’t heard of Feathered Friends, based in Seattle, then do yourself a favor and introduce yourself. This premium-down bag was keeping testers warm in the mid-30s. Through adding less than two pounds to a backpack, these bags offer enormous warmth and security to climbers.