Hispar 500 Down Sleeping Bag: K Series

Warmth to weight taken to the limit with our 'K Series' version of this mountain lightweight for cold conditions. Ideal for fast ascents and quick travel.
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.
-15°C / 5°F
For clothing, weight is for size: M. For sleeping bags, weight changes with selected length/width. N.B. there may be some variation in the weights of finished products.
770g / 27oz
Hispar 500 Down Sleeping Bag: 'K Series'

I tried out the this bag during the Everest Trail Race. I was toasty warm every night, even on the coldest nights.

Alice Morrison. Read full review.



  • PHD 'K Series': Ultimate warmth/weight performance
  • Unique PHD 1000 fillpower Down
  • Outer: Ultrashell water-resistant fabric. An excellent balance of weight, water-resistance and breathability
  • Inner: Superlight 10X fabric. Down-proof, wind proof and super soft
  • Box-wall construction for max loft
  • Short zip protected by double draft tubes
  • Pack size: 20 x 34 cm†
  • Straight-wall baffles for lightness
  • Side block baffles to prevent down shift
  • Extra down channels along each side ensure side insulation
  • Oval footpiece to fit naturally to feet and avoid pressure
  • Mummy hood draws up close around head
  • Collar seals in warmth at neck
  • Stuff sac with mesh storage bag
  • Options:
    • Waterproof Dri-LX outer fabric shell (+250g)‡
    • Slim, Wide and Extra Wide widths*
    • Short, Long, and Extra Long lengths*
    • Full zip (left or right)
    • Further customisation available via our Design Your Own Sleeping Bag service

†Please note: We make our stuff sacs big enough to allow fairly easy stuffing rather than reducing the bags to the tightest minimum.

‡Please note: The optional waterproof Dri-LX outer provides an extra seam-sealed outer shell to the bag. While a shelled sleeping bag is not designed to be used alone in heavy rain (the hood area is open to the elements) the shell does protect the bag when it is used outdoors without a tent.

*Please note: For all length or width options, we change the amount of downfill to keep the warmth (TOT) the same.


This K Series product has been created for one single reason, to take warmth-for-weight performance to the limit of what's possible. Unique 1000 down, super-light materials, and specific design features mean that the word Ultralight now applies to this wide range of gear that will take you to the Poles as well as on a Sahara Marathon. More on the K Series...

Ultralights for the mountains is what we have always called Hispar sleeping bags and even with the new K Series versions it's hard to find a better way to describe them. Perhaps 'Ultralightest' would be closer if it wasn't such an awful word.

The combination of this bag's design with the superlative quality of our 1000 down and our new fabrics, Ultrashell and 10X, almost send the Hispar K range off the scale for warmth/weight performance.

  • The straight-wall baffle system (as used on the Minimus) is the lightest available.
  • The close-fitting mummy hood borrowed from the high-performance bags brings a snug protective feel.
  • A short zip with a double draft tube is standard on these bags (a zip is necessary with a mummy hood), and side block baffles have been inserted to prevent down shifting between top and base.
  • The outer V baffle at each side protects the side seams and increases the inner/outer differential to allow the down full loft.
  • A simple internal collar completes the technical specifications.

The weights of the Hispar K bags are graphic evidence of the effectiveness of this specific design. With the added performance of our 1000 down these bags deliver the greatest possible warmth per gram.

The optional waterproof Dri-LX outer provides an extra seam-sealed outer shell to the bag. While a shelled sleeping bag is not designed to be used alone in heavy rain (the hood area is open to the elements) the shell does protect the bag when it is used outdoors without a tent, for example in a snow-hole or under a tarp.

As used by Jo Meek on the Everest Trail Race.

Dri-LX (weight: 64 gsm)

At just 64gsm, Dri-LX is our lightest 2-layer breathable waterproof rip-stop nylon fabric. Its remarkably low weight not only makes for a lighter load, but also reduces pack size. Its excellent waterproofing qualities are in part due to how it can be taped at the seams to create a waterproof shell for sleeping bags and clothing.

Ultrashell (weight: 40 gsm)

One of the lightest of PHD's coated materials. This ripstop nylon provides complete wind block and good water resistance at minimal weight. Ultrashell gives an excellent upgrade to performance with very little weight penalty.

Ultralight 10X fabric (weight: 26 gsm)

10X, PHD's first 10 Denier Fabric. 9,000 metres of the yarn used to weave 10X weighs just 10g, that's about the same as a £1 coin! For all its thinness 10X is amazingly downproof and with reasonable care will go on giving you good service for years.

Sleeping bag zips

  • No zip: The standard design on our lightest bags with open hoods. The simplest/lightest system which is a must for adventure racers. Up to 140gm (5oz) lighter than a full zip with draft tube.
  • Full zips: Full zip bags ventilate well, so they can be used over a wider range of temperatures.
  • Short zips: Short zips are lighter and pack smaller than full zips. A short zip & draft tube is up to 85gm (3oz) lighter than the full version.
  • Our full briefing on sleeping bag zips.

1000 fillpower down

This rarest of all downs we reserve for the K Series. European goose down of unique quality. 1000 provides the highest warmth-for-weight performance possible from down. More on our down insulation.


This bag has an insulating straight wall baffle system throughout (no straight-through stitching). Straight wall is the lightest of all baffle systems. In cross section it looks like this:

Side V channels, and double draft tubes behind the zip optimise insulation.

More on sleeping bag construction.

"I tried out the this bag during the Everest Trail Race. I was toasty warm every night, even on the coldest nights. The other thing that I thought was excellent was that the bag was dry in the morning. My tent mate had a different brand and although she was also warm her bag was soaking every day as her body heat caused condensation."
Alice Morrison. Read full review.

"My Hispar 500 K is awesome, used it first time on Mont Blanc in October this year."
Kevin Bloor

The reviews below relate to standard Hispar 500, which is 145g heavier

"The lightest bag tested yet warmer than some ... The Hispar 500 really does deserve the description 'Ultralight' ... The loft really is astonishing for such a lightweight bag ... the Hispar 500 is my favourite of the bags tested."
Chris Townsend, Winter Down Sleeping Bags test, TGO Magazine.

"I took a PHD Hispar 500 on a 10-night trip to the Patagonian ice cap. The Hispar's lofting ability was extremely impressive. The bag's outer was pleasantly resistant to tent condensation and sleety drizzle. At only 900g its warmth-to-weight ratio seems unbeatable. Worth every penny for icy wild camping."
Chiz Dakin, Review in Trail Magazine.

"I used a Hispar 500 Down Sleeping Bag on the Imperial College Reru Valley expedition. The Hispar 500 has an excellent temperature range, and was comfortable both on a glacier at 5700m and at basecamp on the valley. It packed small, was incredibly light and hugely versatile."
Jonathan Moodie - Imperial College Reru Valley Expedition team leader (Zanskar Himalaya, India)

"The Hispar 500s were very warm, light and packed with relative ease. Even with condensation and freezing on the outer surface of the bag (-20C), very comfortable sleeping temperatures were maintained in the bag."
Jonathan Phillips, Imperial College, Obra Valley Expedition (GARHWAL HIMALAYA, INDIA)

"Thank you for the fantastic equipment. Everything (including the Hispar 500 down sleeping bag) was above and beyond what was required and fended off the elements perfectly."
Graham B, on a trip to Aconcagua.

"I'm very pleased with my Hispar 500."
Jake L

"It gives a nice snug fit without being too restrictive. What really impressed me was the amount it lofts, the 1000 down appears to really do its job. Once out of its bag it grows and grows and grows! It's amazing that such a light bag can be so fat. I was sad enough to weigh it with it coming in at 935 grammes with stuff sack, pretty light for a -15 C rated bag with a water resistant shell. I can be an outdoor shop customer from hell inspecting every seam and stitch of everything I buy (usually being pretty unimpressed by the poor construction of kit these days and often finding fault). However so far I have not found even so much as a loose thread."
Review at Backpackingbongos.

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