Xero Half Bag

Our extreme expedition half bag (pied d'elephant) to insulate legs and feet. Combine with suitable expedition down clothing. Camp down to -30°C and bivvy down to -40°C.*
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.
-30°C / -22°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
Xero Down Half Bag

I was pretty toasty in my Xero Half Bag... it will undoubtedly be my go-to camping kit for many seasons to come"
Marcus Baranow



  • Outer fabric (including extender): water-resistant Ultrashell
  • Inner fabric – Ultralight MX
  • Rare 950 fill-power European Goose down
  • Box wall construction to allow full loft
  • Neck-length fabric 'extender' to cut drafts
  • Side block baffles to prevent down shift
  • Extra down-filled side V channels along each side ensure side insulation
  • Oval foot-piece for comfort
  • Reflective strip for night location
  • Draw-cord with cord locks at the waist and top of extender
  • Stuff sac – 20 x 34cm
  • One size fits all


Camp down to -30°C and bivvy down to -40°C.*

Our extreme expedition half bag (pied d'elephant) to insulate legs and feet. Combine with suitable expedition down clothing to save weight and reduce pack-size. The use of pied d’elephant or Halfbags for lightweight bivis and camping is well proven in the mountains. Here we’ve added a neck length fabric “extender” to cocoon your body, arms and hands to reduce cold air ingress.

Half-bags are back

Half-bags (Pied d'elephant to oldies) are coming back. They've been out of fashion for many years in the trend towards using lifts and huts to make quick comfortable ascents, when a bivouac was a mistake, not a plan.

But the logic behind half-bags is still valid. If you're wearing a warm jacket already, all you need to spend the night out is something to keep your legs warm and there's no lighter way to do that than to use a half-bag. Check out the weights of PHD's half-bags and see for yourself.

  • Deep winter bivvying and snow-holing when paired with a suitable jacket
  • When you want a lightweight backup in case weather, miscalculation or accident catch you out

...A half-bag is the lightest answer.

*Note on Temperature Ratings

We have given two separate TOTs (Typical Operating Temperatures) for this half-bag.

  • 'Camp' is for the times people might want to use it for lightweight camping instead of taking a sleeping bag (an appropriate jacket and ground insulation is assumed): this is a standard TOT, meaning you should be able to get a good night's sleep under normal circumstances.
  • 'Bivvy' gives a range of temperatures from the usual doze level down to the point beyond which you're liable to be awake and getting cold. Again an insulated jacket is needed.

All these figures assume you are wearing normal clothing inside the half-bag. Any insulated kit like down trousers and down socks will improve the TOT. Don’t forget, the down jacket needs to be warm enough to sleep in.

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.

Superlight MX fabric (weight: 32 gsm)

A mini-ripstop nylon with excellent tear strength, MX is the pick of the superfine 15 denier downproof materials. We have tested lighter fabrics, but most have had significant drawbacks, while our confidence in MX is based on several years of extensive use in both our ultralight and our high mountain gear.

950 fillpower down

A newcomer to our range. European goose of rare quality. A high value alternative at the top levels of performance. More on our down insulation.

"I was pretty toasty in my Xero Half Bag paired with the Rondoy Down Jacket: K Series in -20°C tonight on my deck in Lake Louise. At a combined weight of only 1225g (725g for half bag, 500g for jacket) and the fact I'd be taking a base camp down regardless, it will undoubtedly be my go-to camping kit for many seasons to come! [In a second test Marcus says] worked great at -26°C on an empty stomach"
Marcus Baranow

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