The PHD M.Degree 400 K custom-made bags are for those who demand the best warmth-to-weight ratio, and who are prepared to pay for it, says Fiona Russell.

PHD makes all of its products from start to finish in a UK factory. The company sources more than 95% of materials and components within Europe and minimises global transportation. The down is ethically sourced by PHD itself. This goes some way to explain the fairly eye-watering price of the PHD M.Degree 400 K custom-made, but it’s also a fully custom-made bag. As such, it fits me like a glove in width, length and at my feet.

Slipping inside the bag is immediately cosy, and it’s easily the warmest bag I’ve tested. It’s also the lightest, and to achieve this PHD uses a different construction on the top compared to the underside to “optimise down lofting and shed excess bulk”. Weight is further reduced by the lightweight and wind-resistant nylon lining and shell fabric. I also chose a short zip.

The hood is smaller and more basic than other bags, and whilst it can be cinched around the neck it doesn’t have baffles.

A couple of niggles include a sticky zip, and a drawcord for the hood adjuster that sits annoyingly in front of the face. Additionally, the narrow fit means stretching my legs whilst sleeping is not possible.  

PHD custom-made bags are for those who demand the best warmth-to-weight ratio, and who are prepared to pay for it.

Discover more of the best sleeping bags for women as tested by The Great Outdoors gear expert Fiona Russell.