Denali Down Jacket: K Series

A superlight high-altitude mountaineering and polar jacket for light ascents and fast 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.
-38°C / -36.4°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.
725g / 26oz
Denali Down Jacket: K Series

Faultless, brilliant bit of kit and I could comfortably stand around for hours at -30°C without getting cold.
Lou Rudd MBE. Used jacket on 1st British solo, unsupported Antarctic traverse



  • A PHD K Series product: Ultimate warmth / weight ratio
  • PHD's Unique 1000 fillpower down
  • Water-resistant Ultrashell outer fabric. An excellent balance of weight, water-resistance and breathability
  • Superlight 10X inner fabric. Down-proof, wind proof and super soft
  • Box-wall construction for maximum loft
  • Front closure:
    • 2 way zip
    • Outer zip baffle with intermittent Velcro + a 3/4 length internal baffle
  • Hood:
    • Box walled
    • Elastic face cord
    • Wired Peak
    • Volume reducer
    • Zip on
    • Helmet-sized
  • Adjustable Velcro cuff closure
  • Elasticated inner back for fit
  • Fleece lined collar
  • Pockets:
    • 2 zipped chest pockets
    • 2 hand warmer pockets
    • 1 internal large zipped security pocket
    • 1 internal water-bottle pocket
  • Stuff sac
  • Pack size 17 x 28cm
  • Options:
    • Custom sizes for a perfect fit
    • Waterproof Dri-LX taped outer shell (adds 175g, +£160). Available in red, green, black or all white.

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


Also available in custom sizes. We make clothing to order, so if you’re not a standard size we can make it to fit. To order a non-standard custom size, select the Custom Sizing tab, choose your body width, and then the body/arm lengths, shorter or longer, that work for you. A custom size takes us a little longer (typically two weeks longer) to make and, because it’s personalized, it’s non-returnable and our customer loyalty scheme can’t be applied.

The Denali Down Jacket is designed for high altitude mountaineering and fast polar expeditions. This incredibly warm and light, full-length down jacket gives substantial protection in the most inhospitable locations.

Already used on 8000m Himalayan summits; by Lou Rudd MBE on the first British solo, unsupported Antarctic traverse; and on Denali herself, the Denali Jacket provides superb performance at the remarkably low weight of just 725g. 

The combination of the Denali Jacket (725g) and the Denali Trousers (430g) used together (1155g), makes for an exceptionally light & flexible high-altitude or polar set.

An optional, fully waterproof taped outer shell (in our Dri-LX fabric) can be selected to protect the down on long and arduous expeditions. The extra layer of fabric adds to the weight and bulk of the jacket but extends its use even further into a wider range of conditions.

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.

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.

"Faultless, brilliant bit of kit and I could comfortably stand around for hours at -30°C without getting cold. Also used it as my pillow every night."
Lou Rudd MBE, using the jacket on the 1st British solo, unsupported Antarctic traverse

"The sizing and warmth fitted me very well. I believe in keeping my core warm, so that I don't get frostnips/bites on my digits. The Denali jacket was very toasty on those summit days and in cold high camps.It summitted Aconcagua and Denali with me."
Phei Sunn, summitted Denali and Aconcagua in the Denali jacket

"The custom-made item could not fit better and the features and workmanship are top-notch. Many thanks to you and your team for your service and quality."

"It's every bit as good as I expected it would be. The custom sizing is great for me as I'm slimmer than average. The cold weather has seen it put to good use and it will be my friend for many winters to come."
Philip Moate

"The Denali jacket was fantastic for my trip to Mongolia. Thank you for working with me to get the sizing right as I think it made all the difference in terms of how functional it was and how warm it kept me. When walking the migration with the herders we had early starts, just as the sun rose, when temperatures were around -40℃! It never really got hotter than -10℃. We were walking at the speed of the slowest goat, so I wore the jacket almost all day when it was cloudy only taking it off when we were heading up a steep hill or when the sun broke through. The outer waterproof shell on the jacket was well worth it as it gave an extra bit of protection against abrasion, useful when you are helping get a belligerent Yak into a trailer or handling an inquisitive golden eagle! As it packed up relatively small it was very useful when tracking the snow leopards, as it was essential to wear when stationary but too hot when scrambling up the mountains or hiking to and from the hides. I also wore it in the city over a thin sweater, as it was easy to take on and off when going between -30℃ outdoors and well heated shops and cafes!"
Wendy Matthews on a trek and snow leopard tracking expedition in Mongolia

Works well with
From 300.31 180g
High-altitude expedition mitts. Light, compressible, comfortable. Designed to allow use...
From 794.59 430g -38℃
Superlight high-altitude mountaineering and polar down trousers for light ascents and...
From 1,763.28 1315g -46℃
Warmth to weight taken to the limit with our 'K Series' version of this...