This is the highest quality bag with the greatest-warmth-to weight ratio in this review. It's the best. It also only weighs in at 28 oz, making it one of the lightest in this review. The only downside is that it can be hard to find. The Kelty Cosmic Down is an even less expensive down alternative, although the Cosmic Down's fill quality is significantly lower and is reflected in the warmth and price of the bag. This women's specific sleeping bag has more down per square inch than its male counterpart and is hand filled with high quality 800 fill Nikwax Hydrophobic Down. The only potential drawback we found is that the shell material is quite delicate and potentially less durable. It also molts down periodically.
Rab Neutrino 400 - Women's Review
Cons: Expensive, awkward drawcords
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Our Analysis and Test Results
This lightweight, minimalist bag is packed with 800 fill ethically harvested Nikwax Hydrophobic down. It packs down small, is lightweight, and keeps you warm. The Neutrino is head and shoulders above the other women's bags tested in this review and is an ideal 3-season bag for a frequent backpacker.
The Neutrino is one of the warmest sleeping bags in this review, second only to the REI Joule 21 and the Sierra Designs Women's Backcountry Bed 700. Rab notes that it is EN rated at 37 F degrees, for comfort with a limit of 27 degrees F; we find the EN limit rating of 27°F to be right on the money. We tested this bag in Yosemite Valley on some cold nights in September, where temperatures fell below freezing some mornings, and we felt warm in this bag inside a tent.
Rab makes its women's sleeping bags 5-7 inches shorter in length and slightly slimmer than their men's sleeping bags, but use the same amount of down fill for both. This means that the women's bag has more down per square inch and is warmer than the men's version. The cozy neck baffle and draft tube along the zipper kept out the cold air well. Paired with the Therm-a-Rest NeoAir XLite - Women's and you'll have a great lightweight, compact, 3-season backpacking sleeping kit. The Neutrino only has 14 ounces of 800 down fill, but it should be said that it is just as warm as the other down sleeping bags we tested with lower quality 650 fill, such as the Marmot Angel Fire and the Mountain Hardwear Heratio that have 23 and 24 ounces of fill respectively.
Weight is the category where the Neutrino excels far above all other bags in this review. Rab has made a great effort to minimize the weight of this sleeping bag by paring down its features and materials, but still retains the necessities.
Weighing only 28 oz, or 1 pound 12 ounces, it is a pleasure to pack this sleeping bag in your backpack. By using high quality down, the bag can be very toasty without being bulky or heavy. We think that Rab could have used a ¾ length zipper as they have on past Neutrino models to cut down the weight of this bag even more. The shell material is very lightweight, which is great for weight savings, but is consequently quite delicate and seems more prone to molt down, which is a drawback.
The Neutrino is very comfortable. It is roomy enough for a mummy bag that we didn't feel constricted, and its shell and liner fabrics feel light and soft against the skin.
The bag even has an ergonomically shaped foot box so there is space for your feet as well as any wet socks or boot liners you may want to stuff in there to dry overnight. If mummy bags feel constrictive to you and you want a bit more wiggle room, check out the Big Agnes Roxy Ann 15, which has a more rectangular shape, or the Backcountry Bed 700, which offers a built-in comforter.
Once again, the high quality down is to this bag's benefit, because it compresses to a small size. This bag comes with an interesting dry bag compression stuff sack that helps you compress the bag to be quite small.
The stuff sack has an inner compartment with a drawstring to stuff your bag into, and then it finishes with a roll top closure, to ensure your bag will not get wet during the day's hike. This bag could potentially be compressed more with a traditional compression sack if you need to create even more space in your pack. It also comes with a cotton storage sack so you can store it away uncompressed to help keep its loft.
At first glance, this bag does not appear to have many distinct features. It is just a big, pink tube. But look closer, and you will discover that many features are hidden just below the surface — literally. The main feature that Rab has introduced for its Neutrino line is Nikwax Hydrophobic down. This down treatment has been specially formulated between Rab and Nikwax in an attempt to make the down absorb less water, dry faster, and retain its loft longer. This treatment does not make the bag waterproof, nor does it take the place of synthetic insulation in wet conditions, but rather allows the bag to function at a higher level for a longer period when the weather is not ideal.
We think it has great potential for users who are camping in a situation where body moisture and condensation may penetrate your sleeping bag (in a winter camping or wet tent situation), or if you are on extended trips where you may be sweatier or greasier than usual. The treated down may help maintain the loft and therefore the warmth of your sleeping bag for a longer period. See our article How to Choose the Best Backpacking Sleeping Bag for more details on Hydrophobic down. All of the down sleeping bags we tested now come with some hydrophobic down.
The Neutrino also has more visible features like the small stow pocket right behind the zipper for you to stash your headlamp or contact case on cold nights. We found the drawcords around the face and neck awkward to use and wish they used two separate diameter cords like on the Slumberjack Boundary 20 - Women's. We also like that the inside of the bag is a lighter color so you can more easily locate your missing black sock.
The Neutrino is an excellent lightweight option for your rugged backpacking or mountaineering trips where weight saving is key, but temps could get down into the thirties. You can also take it along on mellower overnight trips or car camping trips; however, it is quite delicate, so you'll want to be careful with its exterior materials.
Since the Neutrino is one of the warmest bags, it also is one of the most versatile. We think this bag is easily a 3-season backpacking bag when you pair it with a sleeping pad with a decent R-Value such as the Therm-a-Rest ProLite Plus Women's. The hydrophobic down may allow this bag to stand up to a wider variety of conditions than other non-treated down bags. Going light enables backpackers to go faster and farther, which is versatile in itself. This award winner will serve you well on adventures for most of the year, except in winter.
This is one of the more expensive bags in the review, priced at $385. It is similarly priced to similar quality and temperature rated bags by other high-end manufacturers that do not feature hydrophobic down, which makes this bag look like a deal. Our testers love this bag and think it has a lot of great features to compete with some of the lighter sleeping bags on the market. If you are looking for a lightweight bag that could perhaps give you that extra edge with hydrophobic down in damp or dirty situations, this may be what you're looking for. If you are looking for a less expensive down sleeping bag, you could check out the Kelty Cosmic Down 20 - Women's, although it uses lower quality 600 fill hydrophobic duck down, or for a step up check out the Mountain Hardwear Heratio.
This bag wins our Editors' Choice award because it is constructed with high-quality materials and is warm, comfortable, and quite versatile. It is hand-stuffed with 800 fill Nikwax Hydrophobic down and is the lightest and smallest bag in this review. Although long-term tests are inconclusive on the effectiveness of hydrophobic down, the potential to increase your comfort on long, damp trips is intriguing. Remember, ounces equal pounds and pounds equal pain - so save yourself some pain and go with lightweight gear when you can!
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