Xero Down Jacket: K Series

'K-Series' version of our high-altitude expedition jacket. Light enough for the ascent, warm enough for when the mercury freezes. Warmth to weight at the limit of possibilities. Now also available in custom sizes.
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.
-40°C / -40°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.
1130g / 40oz
Xero Down Jacket: K Series

Peter Hutchinson makes probably the best down gear in the world and his Xero jacket has kept me happy (well as much as you can expect to be) deep into the minus 40 degrees.
Nick Lewis, Climb Magazine.



  • PHD 'K Series' Product: Ultimate warmth / weight performance
  • Unique 1000 fillpower European Goose down
  • Water-resistant Ultrashell outer. An excellent balance of weight, water-resistance and breathability
  • Superlight 10X inner. Down-proof, wind proof and super soft
  • Box-wall construction for maximum loft
  • Differential Cut allowing full down loft
  • Shoulder and top arm reinforced with tough waterproof HS2 fabric
  • Pockets:
    • 2 handwarmer pockets
    • 2 inner water-bottle pockets with elasticated entry
  • Front closure:
    • 2 way zip
    • Protected by double baffle with intermittment velcro
  • Hood:
    • Large size with rear volume reducers
    • Fleece-lined collar
    • Elastic face cord with cord end channels
    • Adjustable front velcro closure
    • Zip-on
  • Arms - both layers articulated
  • Elasticated waist and elasticated inner back for snug fit
  • Cuffs: velcro closure
  • Reflector tape on pockets and back of hood for night searches
  • Beard flap
  • Mitt attachments at chest
  • Stuff sac
  • Pack size: 20 x 34cm* 
  • Options:
    • Sewn on hood

*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.

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...

An even lighter version of our Xero Jacket. With box-walls, expedition-style pockets inside and out, a voluminous hood and many other features, the 'K Series' Xero Down Jacket has full expedition capability at minimal weight and packed size. Designed to provide exactly what is required on rapid high altitude ascents or lightweight arctic travel for expeditions. Suitable for those who are opting for the versatility of separate down garments over one piece suits. Insulation level is similar to the Xero Down Suit with the Standard fill.

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.

Waterproof HS2 outer fabric (weight: 88 gsm)

HS2 is a 2-layer laminate, a high-spec option for the outer layer of our insulated gear. This ripstop fabric strikes an excellent balance between lightness and durability. It is light enough for our Belay tops and tough enough for expedition use in our Omega clothing, while the Kappa clothing makes full use of both its qualities. HS2 is completely waterproof (when the seams are taped) and offers excellent breathability. (Weight: 88gsm).

"Peter Hutchinson makes probably the best down gear in the world and his Xero jacket has kept me happy (well as much as you can expect to be) deep into the minus 40 degrees."
Nick Lewis, Climb Magazine.

"My Xero Jacket was back out in force this summer on two trips to Mt Elbrus. It performed superbly and kept me toasty warm despite the conditions."
Adele Pennington.

"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.

"Just a quick note to let you know that ALL 5 members of our team reached the Summit of Cho Oyo (8201m). Another member of the team wore [your] Xero Down Jacket and ... was comfortable and impressed. Thanks for the great gear."
'Lanx', Equipment buyer, UK Reserve Forces Seven Summits team.

"The Xero jacket was perfect for summit day where we had a combination of -25C and 20 knot winds and the thigh-length design meant that I never needed to wear the Xero trousers. It is the best down jacket I've ever used."
Nick Lewis, Antarctic Logistics and Expeditions.

"Very happy to report that the Xero Jacket performed fantastically and kept us warm and safe especially during summit day where temperatures dropped below -30 deg C."
Robert Gatt, Challenge8000, on Cho Oyu.

"Just a short note to thank you for making my Xero down jacket in super quick time. I am over the moon with it. What a pleasure to buy from committed experts. Never again the usual naff US brands where everyone knows they are made to far eastern specifications, in other words as cheaply as possible. I am still grinning."

"Many thanks for the Xero Jacket for Cho Oyu which worked very well."

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