Delta-Race 100 K Down Sleeping Bag

Whisper-light 10°C bag. Featuring 18g/m2 Vertex fabric & high lofting down with hoodless design & hybrid construction for minimum pack weight & maximum warmth.

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.
10°C / 50°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.
200g / 7oz
Delta-Race 100 K Down Sleeping Bag


  • Hoodless for lightness
  • Exceptional 1000 fillpower goose down
  • 18g/m2 Vertex fabric throughout
  • Box-wall construction on the top for maximum loft
  • Stitch-through construction on the base for minimum weight
  • Pack size*: 10 x 18cm
  • Oval footpiece: fits naturally to feet and avoids pressure
  • Adjustable cord with cordlock at the shoulder
  • Stuff sac & mesh storage bag supplied
  • Options:
    • 4 different widths for the perfect fit: Slim, Std, Wide and Extra Wide†
    • 4 different lengths for the perfect fit: Short, Std, Long and Extra Long†
    • Hypershell water-resistant outer (+£35)
    • Waterproof Dri-LX outer fabric shell (+200g, +£165)
    • Waterproof footbag cover:
      • Stud on (+£35)
      • Sewn on (+£35)
    • Zip options:
      • Full zip (left or right)
      • Short zip (left or right)
      • Foot zip (left or right)

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

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


Just when you thought a sleeping bag couldn’t get any lighter …. The Delta-Race 100 K is the lightest bag PHD have ever made. And, at 200g, probably the lightest sleeping bag in the world. Created for self-support ultra-runners, elite mountain marathon racers, lightweight backpackers – anybody who demands every ounce of performance from the kit they carry. This whisper-light bag packs into a pocket-sized stuff sac, taking up a minuscule amount of space in your rucksack.

Using 18g/m2 Vertex fabric and 1000 fillpower goose down (our rare, exceptionally high-grade insulation) allows us to create a superbly lightweight bag, and the specialist dual-construction design and neck length dimensions make this the most extreme example of its kind.

The top of the bag uses box-wall construction to allow optimum down lofting, and stitch-through construction on the base sheds excess bulk, working with your ground insulation mat to deliver the incredible weight saving performance. 

As with all PHD sleeping bags, the Delta-Race 100 K is made to order, so we can offer plenty of options. To begin with, a combination of 4 different lengths and 4 different widths allows you to get the perfect fit. A perfect fit is important because poor sizing compromises insulation, and you don’t want to carry excess material, do you?

The outer fabric can be upgraded in various ways:

  • By replacing Vertex with our water-resistant Hypershell fabric. This helps deal with the condensation that can form on the inside of a tent or bivi.
  • By adding a waterproof Dri-LX outer, which provides an extra seam-sealed outer shell to the bag. While a shelled sleeping bag is not designed to be used on its own in heavy rain (water will find its way in), the shell does protect the bag when it is used outdoors without a tent, for example in a snow-hole or under a tarp.

Furthermore, because touching the inside of a tent can cause dampness around the foot of sleeping bags, an optional waterproof foot cover can be added for extra protection. This can be sewn on or – so you can detach it and strip the bag right down for super-minimalist overnights – we can make it stud-on: it’s up to you. Note: there is no need for this foot cover if you have selected a waterproof Dri-LX outer.

Half- and full-length zip options allow greater flexibility in varying temperatures, while the foot-zip option is the ultra-light way to cool warm feet. Of course, to maintain minimum weight and pack size we’ve selected super-light zips.





Water-resistant HyperShell fabric (weight: 28 gsm)

HyperShell is PHD’s exceptionally lightweight waterproof coated fabric. This remarkable ripstop nylon provides complete windblock and good water resistance at a breath-taking weight (28 gsm). HyperShell protects the down from condensation drips found typically in tents, tarps and snow-holes, but its very low weight allows greater lofting of the down and a smaller pack size. Hydrostatic head: 1000mm.

Note: unlike some other so-called 'proofed' fabrics, HyperShell does not rely solely on a DWR (durable water repellent) coating. Although it has a DWR coating, more importantly it has a breathable and permanent PU coating applied on the underside of the fabric that cannot be abraded through daily use, so performance is maintained over many years.

Foot zip

For the lightest and smallest pack a sleeping bag without any zips is king, but for those with warm feet, or even race blisters, a foot zip can be more than just a little luxury. Adding only 10-12g to the total weight of the bag, the foot zip is the ultralight route to comfort.

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.

Ultralight Vertex fabric (weight: 18 gsm)

Breathtakingly light at 18 gsm, Vertex is the ultimate in technical fabrics for extreme weight saving. This fabric is down-proof and superbly wind-proof and represents a high-point in the development of lightweight technical fabrics. The result of years of evolution and testing, this whisper-light fabric opens up new possibilities at the pinnacle of lightweight gear design

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 on top (no straight-through stitching). Straight wall is the lightest of all baffle sytems. In cross section it looks like this:

On the bottom stitch-through seams are used to minimise weight. More on sleeping bag construction.