Rab Neutrino 400 Review

The Rab Neutrino 400 is the mid weight bag in Rab’s redesigned Neutrino review. With a temperature limit down to -7C its a great bag for 2 to 3 season use in the UK. I’ve been using one for a few weeks, first off on an overnight trip to the Lakes. With temperatures dropping to around -1 over night due to clear skies and the fact that its still early April I was pretty glad of a warm down bag.

Cold and bright morning at Pavey


The Neutrino range is filled with 800FP Goose Down from European sources. The down is then treated with a fluorocarbon free hydrophobic chemical. This is intended to improve the loft of the down in damper conditions i.e the UK, where down insulation traditionally performs poorly. Having lucked out with the weather, the conditions were not very damp so I’m yet to test this.

The bag does loft up very quickly after removal from the stuff sack (more on this later) and was pretty much ready to go after a couple of minutes and a shake out. As a very active sleeper who tends to roll around a lot one thing I did notice was as I rolled over, the area of bag that had been compressed under me very quickly lofted back up, preventing a cold spot.


The Neutrino 400 uses Pertex Quantum outer fabric. This super light fabric is windproof and has a DWR chemical treatment so it does not absorb water. The liner is a lightweight ripstop nylon which feels comfortable against the skin. and features an anti snag zip guard.

The lightweight fabrics and 800FP down create the strangest feeling of warmth without any weight. I was sat in a freezing tent with my breath misting up, but feeling comfortably warm without the usual feeling of weight around you.

The Shape is quite tapered with the area around your shins being quite narrow. However the feet and torso feel much roomier than some other brands so overall you do not feel constricted.

Alfresco breakfast in Langdale


Rab have added some nice features to the new Neutrino bags. The most obvious one is the new chevron baffle design. This allows more of the bag to be covered by less baffles. Baffles means stitching and stitching means colds spots, therefore less baffles means less cold spots. They also reduce the amount of down that will move round to the sides of the bag in the night.

Inside the hood and around the neck is a shaped down filled collar. It looks like a complicated fabric patterning and stitching flex on their rivals but wow does it do a good job of keeping the warmth in.

Collar: We are Rab – The complex stitching people.

By using lightweight materials and high quality down the pack size is very impressive. The Neutrino 400 is available in regular and XL. I’m 6 foot so have been using an XL, which I would definitely recommend if your are bang on 6 foot or taller. The pack size of the XL is obviously a little larger than the regular but it still only takes up around 3L of volume. The Neutrino comes with a waterproof rolltop stuff sack. The stuff sack is shaped longer and narrower than most so will work well in Bike Packing luggage too.

XL Rab Neutrino with a 1L MSR Windburner

In all the Neutrino 400 is an excellent lightweight bag for 3 season UK conditions and summer Alpine trips. It gives you an amazing amount of warmth for under 1kg and is actually comfortable and roomy unlike some ultralight racing suffer-fest bags.

The construction is very lightweight, which is great if you are in a tent and you have some protection between you and rocky ground. If you are looking for something burlier there is the Neutrino Pro range which are essentially the same design at the Neutrinos but with a much burlier outer fabric. Go for a Neutrino Pro if your a big fan of biving (grim!).

View All Rab Sleeping Bags>>



Leave a Reply

Your email address will not be published. Required fields are marked *