Sleep systems

Racing: System 2

The Filler bag is one of PHD's unique designs for Sleep Systems. It softly fills the spaces inside the main sleeping bag and increases the warmth by 10°C. A simple and effective booster at minimum weight.
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.
-2°C / 28.4°F
Schematic representation of Sleep System. Actual components differ.


  • System Products:
    • Main Sleeping Bag: Minim Ultra K (Sleep Rating: +8°C / +46.4°F) Weight 330g/12oz.
    • Plus Item:
      • Filler Down Sleeping Bag
  • Full System Sleep Rating: -2°C (28.4°F)


This is a very simple system which will cover most spring to autumn races in the UK. The Ultra is a great summer bag, but slipping the Filler bag inside will extend its performance down to -2°C. And on top of that the Filler bag works well on its own in night-time temperatures around +15°C, offering a completely separate and ultralight (240g) option for warm summer races.

Review relates to Minim Ultra K Sleeping Bag

"I would, without a doubt, use the PHD Minim Ultra again. Quite simply, I don't think there's a better bag on the market for warm weather stage racing."
Bryon Powell – member of 1st American team to place in top 3 of the Marathon des Sables.

Review relates to Filler Down Sleeping Bag

"I have a long-held belief in the 'layering principle' extending into sleeping bags. PHD's bags suit a multitude of adventure activity situations including:

  • Expedition sea kayaking
  • Himalayan style trekking where you travel through a wide range of temperature zones
  • Cycle touring where there is a similar packing issue to sea kayaking and potential for travelling through temperature zones
  • Plus, anyone who needs to use their sleeping bag across seasons. E.g. Just 'layer up' to convert your summer bag into a 'winter warmer'
During recent sea kayak expeditions in Greenland, my PHD Combi, Minimus, and Filler bags were tested in temperatures ranging from just above freezing to as low as -10°C. It is a pleasure, when you know the temperature is dropping, just to slip into another bag and double the warmth factor."
Sam Cook.


Sleep system components

Works well with
From £504.00 330g +8℃
Warmth to weight at the limit of possibilities with the upgraded 'K Series' edition of this mountain marathon runners' and extra-keen backpackers' favourite.
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.