Xero Down Suit: K Series

'K Series' version of this high-altitude expedition suit. Light enough for the ascent, warm enough for when the mercury freezes. Warmth to weight at the limit of possibilities.
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.
1535g / 54oz
Xero Down Suit K Series

Fantastic ... felt toasty at -25C even when the wind picked up. It was a pleasure to live in them day and night.
Olga Kotova - using Xero down suit on Everest.



  • 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
  • Tough HS2 fabric reinforcement at knees/bum & sleeve/shoulder
  • Front closure: 2 way zip covered by double baffle and Velcro
  • Short side zips (ankle to knee)
  • 6 pockets:
    • 2 cargo pockets
    • 2 handwarmer pockets
    • 2 inner water-bottle pockets with elasticated entry
  • Hood:
    • large size with rear volume reducer
    • elastic face cord with cord ends channels
    • sewn on with adjustable front velcro closure
  • Arms and Knees articulated
  • Rainbow seat zip for toilet access
  • Elasticated waist and elasticated inner back for snug fit
  • Warm knitted cuffs
  • Internal braces - adjustable for varied clothing - removable
  • Reflector tape on pockets and back of hood for night searches
  • Beard flap
  • Mitt attachments at chest
  • Stuff sac
  • Pack size: 25 x 44cm* 
  • Options:
    • Detachable hood (zip-on/sewn-on)
    • Under and Up zip as alternative for toilet access
    • Pit zips (+£50)
    • Thigh-length side zips (+£50)

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


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 Down Suit. The ideal lightweight suit for today's fast ascents. It has seen many summits on Everest and the other 8000m giants. The Xero suit has full expedition specifications, with box-wall construction, expedition-style pockets inside and out, a voluminous hood and many other features. Designed to provide incredible weather protection on rapid high-altitude ascents or lightweight polar expeditions.

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 and choose the body width, body length, inside leg and arm length sizes 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.


Toilet access on suits

  • Under & Up zip: The central front zip on the suit runs from the collar, down the front of the body, past the groin and then under and up to waist level at the back. A two-way zip allows access at any place.
  • Rainbow Seat zip: A rainbow / semicircle zip is sewn in across the backside. A two-way zip allows access and creates a drop down flap.
More on toilet access.

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).

"Fantastic ... felt toasty at -25C even when the wind picked up. It was a pleasure to live in them day and night."
Olga Kotova - using Xero down suit on Everest. Olga was the first woman from a Baltic State to summit Everest.

"Wow, just wow. This is way better than anything Batman or Superman puts on. Truly impressed with the engineered finished product".
Chase Hinckley.

"I ordered a Xero down suit ... off you guys middle of last year. I used [it] on Cho Oyu and [it] worked fantastically ... I did put the gear through a thorough test and am totally happy with the way [it] performed."
Ben Kane, Guide

"Just a quick note to let you know that ALL 5 members of our team reached the Summit of Cho Oyo (8201m). I wore my Xero Down suit with 800 fill on the summit day and [it was] fantastic, the temp was -25C on the summit with a brisk 20-25 knot westerly wind, and I remained cosy warm for the 13 hours it took to get from camp 2 (7200m) to the summit and back down to camp 2. Thanks for the great gear."
'Lanx', UK Reserve Forces Seven Summits team.

"One of the most practical one-piece 8,000-metre down suits available. With six pockets and internal braces reinforced in key wear areas ... Designed by the man who produced the legendary Annapurna duvet jacket, the wind and snowproof Xero sports the same box wall construction found in top flight sleeping bags. Fitted with articulated knees and arms for ease of movement."
Geographical Magazine.

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