This latest edition of Rab’s classic Neutrino 400 sleeping bag was launched in 2022 and appears in our guide to Best sleeping bags for hiking. The most obvious change is the chevron-shaped baffles, which Rab says help to manage the down distribution and also reduce the number of baffles needed, cutting weight.

 Price: £400 | Weight: 849g | Fill: 400g 800FP Nikwax hydrophobic RDS European goose down | Shell: 20D Pertex Quantum recycled nylon ripstop | Construction: trapezoidal box wall | Zip: ¾-length YKK two-way anti-snag | Length: 200cm | Rating: comfort -1°C, limit -7°C | Sizes: one | Men’s version: yes

There’s an improved drawcord system in the hood and neck baffle, which is now much neater and less likely to flop into the face. When testing the Neutrino 400, I liked that the neck baffle was adjustable. Other features include a small pocket inside the hood and a snag-resistant two-way zip. 

The women’s version is smaller than the men’s, which is a weight saving; but if like me you are over 170cm tall it’s a tad short, and it’s also narrow at 156cm girth. The smaller size is more efficient for trapping warm air, minimising cold patches, but some women may find they are more comfortable sizing up to a men’s bag. 

The bag is filled with European goose down, certified by the Responsible Down Standard, at Rab’s factory in the UK. This means that once filled it travels very little distance to the consumer and is never stored packed prior to purchase. This results in spectacular lofting capabilities – although these could diminish a little with use. The tough Pertex Quantum that is used both inside and outside the bag is made from recycled materials and is fluorocarbon-free.  It’s a premium down bag for lightweight use in the shoulder months and even winter.  Expensive, but definitely worth the money.