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 Denali.
As climbing kit, the Xero suit has been to 8000m summits and is rated for -40°C (-40°F). Here it doubles as the night-time booster for the Hispar 600 bag. With the suit worn inside, the performance figure for the bag increases from -21°C (-5.8°F) up to -47°C. The bag should be enough for lower camps by itself, but combined with the Xero suit it will provide enough warmth for comfort and safety at the highest camps on the mountain.
: The 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.