In this sleeping bag product review we specifically look at the Marmot Plasma 30.
These lightweight sleeping bags represent the cream of the crop in terms of light and ultralight backpacking bags under 40 degrees. They use the highest down fill power (800+) in order to achieve the lowest weight and volume. If you’re primary focus is on shedding ounces then you should definitely consider these bags.
Be sure to check the rest of the reviews on the Marmot Hydrogen, The North Face Hightail 2S and the Sierra Designs DriDown Cal 30 sleeping bags.