The Feathered Friends Vireo UL is a specialty bag that is designed for use while alpine climbing. With this goal in mind, this hoodless mummy completely cuts out the zipper to save weight and bulk, and while it has a temperature rating of 25F for the lower body, it uses less down fill on the upper body, which is rated to 45F. The idea is that you will pair it with your insulated belay jacket, which you have to carry on the climb with you anyway, to again save weight and keep you warm during your bivy. At 16.4 ounces, it is indeed very light. While it will serve one well as an alpine climbing sleeping bag, we also found it to be comfortable and enjoyable for use while backpacking as well. The 62" version we tested in our updated review weighs in at 13.9 ounces! The longer 68" version we previously tested also weighed in at less than 16 ounces. We recommend the Top Pick Award winner Vireo to alpinists and cold weather adventurers who climb or hike with a very warm winter parka.
For the majority of ultralight backpackers and thru-hikers, we recommend a quilt for warmth and versatility. The closed foot box quilt Katabatic Gear Palisade 30 is one of the warmest and most comfortable options we tested. If you are more budget conscious, the Enlightened Equipment Revelation 20 fully-opening quilt is one of our top scoring models overall and has a relatively modest price tag.