At the cutting edge of sleeping bag technology is the Plasma from Marmot. Featuring 900+ fill down, it's the lightest and most efficient insulation on the market. Surrounded with 10 Denier Pertex Quantum Fabric, this water-resistant, rip resistant and breathable fabric is as light as the feathers it holds and tough as nails, not to mention down proof so you won't lose any warmth over the years. Its construction is revolutionary, as the baffles run lengthwise rather than across the body moving warm air from your core to the limbs, eliminating cold spots and heating you up faster. Throw in a bevvy of full function features and you've got your new best backcountry friend. Did we mention it's less than a pound and a half?