Marmot Helium

The 15-degree Fahrenheit rating is the lower limit, meaning it is designed to keep you alive at that temperature, not necessarily comfortable. For most sleepers, this bag is ideal for temperatures ranging from 25 to 40 degrees; if you are a cold sleeper, you will want to pair it with a high-R-value sleeping pad.

The 800+ fill power goose down is treated to resist moisture, which helps it maintain loft and warmth if it gets damp from condensation or high humidity. However, it is not waterproof, so you should still use a dry bag or pack liner to keep the sleeping bag completely dry during transit.

The secondary zipper allows you to fold down the top section of the bag like a comforter, which is excellent for temperature regulation on warmer nights. It also makes it much easier to get in and out of the bag without having to unzip the entire length.

While the Helium uses a performance mummy cut to maximize heat retention, it features an anatomically designed footbox that provides a bit more room for your feet to sit naturally. If you are a side sleeper who moves around a lot, you may still find it snug, but it is generally considered spacious for its weight class.

With a compressed volume of 11 liters, the Helium is highly packable for a 3-season bag. It packs down small enough to fit easily into the bottom of most 40-to-50-liter backpacking packs without taking up excessive space.

Choose the Regular if you are 6 feet (72 inches) or shorter, and the Long if you are between 6 feet and 6 feet 6 inches (78 inches). If you are right on the edge of the height limit, opt for the Long to ensure you have enough room to pull the hood over your head without compressing the down at your feet.