I am psyched that winter is on its way, so I can start using the Marmot Lithium Sleeping Bag again. Before I received this sack, I had been using a negative 20-degree option lined with a waterproof shell, from a leading competitor. When I first tried the Lithium from Marmot, I was amazed at how warm it kept me, at almost 2 pounds less in weight. Yeah, yeah, yeah…this is not your choice for Denali, or for Everest for that matter, but for the majority of winter trips I do here in the lower forty eight, you can’t beat it. At 2 pounds, 8 ounces, the Lithium bag is barely noticeable in your pack and compresses nicely due to the 900-fill goose down. The velcro-free face closure is a cool feature as well, and very comfortable.