On a recent multi day trek in Scotland, Jess, a member of our digital team, tried out the Rab Neutrino 400 Women’s down sleeping bag.

Scroll down to see how I got on with this bag, but first, a bit about what makes Rab down bags a good choice….. By meticulously counting grams, methodically measuring insulation, and weathering long nights on frozen summits, Rab’s range of sleeping bags boasts unbeatable performance.

Rab logo on down sleeping bag

All Rab’s sleeping bags feature innovative designs to reduce bulk and improve efficiency, from tapered mummy shapes and snug down draught collars, to lightweight stuff sacks and anti-snag zips. Built with trapezoid baffle construction to maximise the lofting of the down inside and reliable downproof fabrics, all their sleeping bags are built for a lifetime of rigorous mountain use.

Rab sleeping bags  - made in the UK

Made in the UK

All down bags are hand-filled in Derbyshire, this is to ensure the high-quality down is never compressed and remains lofted through from source to consumer.

All the virgin down is independently certified to the Responsible Down Standard. The RDS independently certifies down against animal welfare requirements and tracks it from the source to the final product. This means farming down in environments that allow them to live healthy lives, express innate behaviours and not suffer from fear, pain or distress.

Down offers comfort

Down is naturally breathable, which makes it very comfortable, but the drawback is that it can absorb water. This moisture can overload the fibres, or cause them to stick together, stripping the down of its insulative properties.

To mitigate this effect, Rab applies a Nikwax water repellent “hydrophobic” treatment to the down. This treatment significantly improves the performance of the down by preventing the clusters from absorbing moisture and helping it to retain its loft.

In the event that the down does become waterlogged, the treatment significantly decreases the time it takes the down to dry and its loft to recover.

Nikwax treated down filling


The Neutrino 400 is a lightweight, low bulk bag suitable for cold temperatures and three-season use. It offers exceptional packability and warmth for its weight, and is packed with 400g of high quality 800FP goose down.

The cleverly designed chevron baffles stabilize the down, and reduce the amount of fabric needed compared to horizontal baffles. The trapezoid box wall baffle construction allows the down to fully loft, eliminates cold spots, and maximises warmth. Less weight, and more warmth – win-win!

Additional baffles along the length of the zip and around the neck decrease heat loss, and with an adjustable drawcord around the hood, you can cinch the bag around your face.

800 fill power goose down

The recycled nylon lining and recycled Pertex Quantum outer are wind resistant to help block out the cold and the bag is completed with a ¾ length zip with anti-snag zip guards and a zipped internal stash pocket

Double zip feature

My experience

Weighing only 765g, the Neutrino 400 was a slice of heaven for my weary body. The first surprise was at how small this bag packs down. The storage sack was almost the same size as my 65L rucksack, and I wasn’t sure how it was going to squeeze down into what looks like an 8L drysack. But every morning, like some magic trick, it compressed, and kept on compressing until the finished dry sack size was just bigger than my dry sack full of spare clothes.

Storage bag vs compressed bag sizing – you get both with this sleeping bag

When setting up camp every evening, I made sure to set up my sleep mat and bag, allowing the down time to full loft. The soft material not only helped with packing, but made shimmying into bed quicker. The close-fitting neck baffle trapped in through the cold nights, and the drawcord hood was comfortable around the head and face on the last two nights where the temperature was a lot cooler.

The neck baffle and hood drawcord were easy to locate in the dark and easy to adjust one-handed when bleary-eyed in the morning. The tapered mummy shape, combined with the female specific shape and shorter length provided enough room, without creating any dead air spots and the angled foot box allowed for a relaxed sleeping posture, helping me to sleep comfortable and inevitably move around in the night.

Neck baffle draw cords

Angled foot box design

In summary

The Neutrino 400 has a comfort rating of -1 degrees. Sleeping bag temperature ratings are based on the bag being paired with a suitable sleeping mat for the conditions. By pairing it with my Thermarest TrailPro, designed for 3-season use, I was able to stay warm through the night. As someone who has Reynaud’s, this was very much important!

For the size and weight, this bag packs a lot of warmth. Check out the actual model I used here.

Shop all Rab Down Sleeping Bags