Sleep systems

Vinson: System 1

This system is a serious weight-saver. The Xero clothing is ideal for climbing Vinson. Wear it inside the Hispar 600 and it moves the bag’s performance rating right up to -47°C (the bag in the system is the Wide version to make sure that the down clothing can loft fully). Yet the Hispar bag weighs around 600g (21.2oz) less than a standard bag rated to -47°C and packs down to about two-thirds the volume. The Hispar 600K has even more impressive stats.
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.
-47°C / -52.6°F
Schematic representation of Sleep System. Actual components differ.
“This bag has an unmatched warmth/weight ratio.”


  • System Products:
    • ​Main Sleeping Bag: Hispar 600 (Wide) (Sleep Rating: -21°C / -5.8°F)
    • Plus Items:
      • Xero Down Jacket
      • Xero Down Trousers
      • Xero Down Socks
  • Full System Sleep Rating: -47°C (-52.6°F)
  • Sleeping Bag Weights:
    • Hispar 600 Down Sleeping Bag (Wide): 1154g (40.7oz)
    • Standard lightweight Sleeping Bag to achieve Full System warmth: 1760g (62.1oz)


This system is very similar to the one already used successfully on Broad Peak (see Case Study), but it advises a much warmer sleeping bag. The Hispar 600 only weighs a little over 200g (7.1oz) more than the bag used on Broad Peak, but it gives a greatly increased margin for mishap or bad weather, a necessary precaution on a mountain as remote as Vinson.

As climbing kit, the Xero clothing is rated for -40°C (-40°F) and has been to the summit of Vinson several times. The night-time boost it gives the Hispar bag takes the system rating up to -47°C, warm enough for comfort and safety in the Antarctic summer. 

The clothing in this system is in separate pieces, unlike the suit in System 2. While the one-piece suit is simpler and often favoured for the high Himalayas, separate clothing makes for more versatility and wider usefulness for the kit on trips to lower mountains.

K SeriesThe Hispar 600K Down Sleeping Bag (Wide) is available in the K Series. The exceptional loft of 1000 down reduces the weight to just 982g (34.6oz), creating a unique sleeping bag that still fulfils its -21°C rating at under a kilo pack weight.

This review relates to Hispar 600 Down Sleeping Bag

"This bag has an unmatched warmth/weight ratio ... The draft tubes undoubtedly provide the best insulation behind the zip of all the bags tested – not a trivial detail if you face harsh conditions."
from Carnets d'Aventures Magazine's test of 18 sleeping bags for cold conditions.

This review relates to Xero Down Jacket

"Just a quick note to thank you for the timely supply of the PHD down gear before my Mt Vinson trip. The gear was absolutely first class. I used the Xero 900 down jacket on our summit day which was -26C with a 30-40 knot wind and they were faultless."
Mark Dixon.

"I've just returned from Vinson in Antarctica where your Xero down jacket made life a breeze."
Lord Forsyth, former Secretary of State for Scotland.

This review relates to Xero Down Trousers

"Your down trousers were lovely to wear in the hard wind outside the tent during our ski tour last week in the Swedish mountains."
Stefan & Susanne Grimfors.

This review relates to Xero Down Socks

"The Xero booties were great for sleeping in and I could also wear them inside my Sportivas for mooching around camp. All in all, perfect."
Nick Lewis, Antarctic Logistics & Expeditions.

Sleep system components

Works well with
From £900.00 1040g -21℃
Mountain lightweight for low temperatures and high peaks. Ideal for fast ascents and quick travel.
From £1,090.00 1250g -40℃
High-altitude expedition jacket. Light enough for the ascent, warm enough for when the mercury freezes. Now also available in custom sizes.
From £653.00 660g -40℃
Designed for fast moving expeditions to the highest levels or for any extreme cold weather venture where weight is at a premium. Now also available in custom sizes.
From £214.00 170g
High-altitude expedition socks. Light, compressible and comfortable. For warmth in high camps.