Sleep systems

Alps Summer: System 3

This is a multi-purpose system, offering a number of options in camp or on the mountain. When the weather's warm, the Filler can be used as a stand-alone bag for camp or bivvy. It also works as a bivvy option at lower temperatures with the Alpine Ultra jacket. And if nights in camp turn really cold, slip the Filler bag inside the Hispar 400 and it will boost performance from -9°C right up to -19°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.
-19°C / -2.2°F
Schematic representation of Sleep System. Actual components differ.


  • System Products:
    • Main Sleeping Bag: Hispar 400 (Sleep Rating: -9°C / 15.8°F) Weight 790g/28oz.
    • Plus Items:
      • Alpine Ultra Down Jacket
      • Filler Down Sleeping Bag (Ultrashell)
  • Full System Sleep Rating: -19°C (-2.2°F)


For daytime use the Alpine Ultra jacket has been called ‘the perfect alpine downie’ and the Filler bag makes a versatile partner. Weighing just 240g, the Filler makes an ultralight bivvy bag on its own. In colder conditions you can fold down the Filler to double thickness and pair it up with the Alpine Ultra jacket for a bivvy down to about 0°C. 

In camp the Hispar 400 bag by itself is rated at -9°C, warm enough for most summer nights in Europe or at low altitudes (like Baffin or coastal Greenland). When colder nights call for it, the Alpine Ultra jacket and Filler bag can boost the Hispar to around -20°C. The system provides a useful safety margin without the need to carry a big -20°C sleeping bag.

K SeriesThe Hispar 400K Sleeping Bag is available in the K Series: performance is the same, but the exceptional loft of 1000 down reduces the weight of the bag to an amazing 655g (23.1oz).

Review relates to Hispar 400 Down Sleeping Bag

"I'm over the moon to say the least. The build quality is excellent and I'm picking the bag up every hour to try and convince my brain that it actually is that light. Consider me a totally satisfied customer, please pass my thanks on to the team."
Rory Abbott.

Review relates to Alpine Ultra Down Jacket

"Alpine Ultra jacket was definitely the "go to" piece of kit for the whole expedition. Quick on, quick off, stuff it in the pack, clip it to an anchor whilst you sort gear. Drishell is durable enough for arm rappels on fixed ropes and definitely proofed enough for high mountain conditions."
Ben Kane, Guide, Field Touring Alpine.

Review relates to Filler Down Sleeping Bag

"I used the Filler Bag in the Alps with great success. I happily slept in it, albeit with a vest and hat on, at temperatures down to around 12 degrees C and was perfectly comfortable. Saved a lot of pack weight. Thanks for a great product, the down you use is obviously of a very high quality."
Mike Jones.

Sleep system components

Works well with
From £781.00 790g -9℃
Mountain lightweight for cool conditions. Ideal for fast ascents and quick travel.
From £538.00 340g -10℃
A climbers' down jacket at the limits of lightness. Even with chest pockets and the optional helmet-sized hood, it's lighter, warmer and packs smaller than fleece. Now also available in custom sizes.
From £486.00 240g +15℃
A lightweight liner that boosts your sleeping bag's warmth by 10°C. On its own, the lightest of sleeping bags. A PHD 'K Series' product: warmth to weight at the limit of possibilities.