Sleep systems

High-Level Treks: System 1

This system combines the superb Hispar 400 sleeping bag with the box-wall Yukon jacket. At night the down clothing will boost the whole system to -24°C when worn inside the Hispar bag. In the daytime the Yukon, with its -15°C rating, offers full protection when the trek goes high, and the trousers will really show their worth in a cold camp.
Typical Operating Temperature
Guideline minimum temperature. Sleeping Bag TOT: you should get a night’s sleep, under normal circumstances. Clothing TOT: you should feel warm enough, assuming low/moderate activity. Sleep System TOT: relates to full system. For more details, see our Technical Briefing.
-24°C / -11.2°F
Schematic representation of Sleep System. Actual components differ.
"This has to be the best sleeping bag I've ever used in every respect."


  • System Products:
    • Main Sleeping Bag: Hispar 400 (Sleep Rating: -9°C / 15.8°F)
    • Plus Items:
      • Yukon Down Jacket
      • Minimus Down Trousers
      • Minimus Down Socks
  • Full System Sleep Rating: -24°C (-11.2°F)
  • Sleeping Bag Weights:
    • Hispar 400 Down Sleeping Bag: 790g (27.9oz)
    • Standard lightweight Sleeping Bag to achieve Full System warmth: 1125g (39.7oz)


Minus 10°C is about the coldest you would expect on most high-level treks such as Everest Base Camp, but nights are capable of dipping to -15°C or even below occasionally. Using Yukon clothing inside the Hispar 400 will ensure your comfort at the lowest of these temperatures. On the higher parts of the trek you're sure to be wearing the Yukon jacket a lot in the daytime, and the down trousers will be a welcome addition around camp.

K Series: The Hispar 400K Sleeping Bag is available in the K Series: performance is the same, but the exceptional loft of 1000 down reduces the weight of the bag to an amazing 655g (23oz).

Review relates to Hispar 400 Down Sleeping Bag

"This has to be the best sleeping bag I've ever used in every respect. It weighs 790g and its warm as a very warm thing (good to -9). It's not cheap but then you get what you pay for when it comes to sleeping bags. PHD are a very small company but they beat the socks off the big guys."
Phil Newby, registered BAIML International Mountain Leader.

Review relates to Yukon Down Jacket

"Many thanks for the jacket that you supplied me for the Yukon Arctic Ultra. [It] performed perfectly in temperatures down to -35°C. The light weight and small size was also a huge help and helped me gain second place in the race. I ... am now the second fastest person over the course and the fastest European."
Dr Stuart Gillet (wearing a prototype Yukon jacket).

Review relates to Minimus Down Trousers

Backpacking Light - Highly recommended

"Overall Rating: Highly Recommended. These down pants are simple and light, just the way we want them. They have the most loft and highest loft:weight ratio of the three pants we tested; I couldn't ask for more. I found that I could extend the warmth of a 30°F (-1°C) sleeping bag to 15°F (-9°C) by wearing these pants and a lightweight down jacket inside."
Will Rietveld, Backpacking Light. Read full review.

Review relates to Minimus Down Socks

"The Minimus trousers and socks are amazing. The combination of weight, compressed volume and insulation properties is outstanding. With down I was able to reduce my pack weight significantly."

Sleep system components

Works well with
From £781.00 790g -9℃
Mountain lightweight for cool conditions. Ideal for fast ascents and quick travel.
From £174.00 90g
Unbelievably light down-filled sock for warm feet in cold tents.