Sleep systems

Mid-Level Treks: 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.
-15°C / 5°F
Schematic representation of Sleep System. Actual components differ.


  • System Products:
    • Main Sleeping Bag: Minim 400 (Sleep Rating: -5°C / 23°F) Weight 670g/24oz.
    • Plus Items:
      • Filler Down Sleeping Bag
  • Full System Sleep Rating: -15°C (5°F)


On a mid-level trek you are likely to encounter night-time minimums of -5°C and sometimes lower. On milder nights the lightweight Minim 400 bag will be enough on its own, but when temperatures fall to -10°C or below, it’s no problem with this System. Slip the Filler bag inside the Minim and it will extend the capability of the Minim 400 from -5°C to -15°C.

The Filler bag does offer advantages of its own. If parts of your trek are in warmer areas, the Filler is rated to +15°C as a stand-alone bag and would probably remain comfortable at close to +20°C, offering an option for warmer nights. It can also act as a good alternative in teahouse or lodge accommodation on nights when you're not camping.

K SeriesThe Minim 400K Down 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 585g (21oz).

Review relates to Minim 400 Down Sleeping Bag

Trek & Mountain - Gear of the Year 2014

"After using a whole spectrum of sleeping bags during testing this year, I am convinced that if you want a lightweight option for backpacking trips then the Minim is hard to beat."
Trek & Mountain magazine gear tester, Paul Smith, selects the Minim 400 in his 'Gear of the Year 2014'.

Review relates to Filler Down Sleeping Bag

"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 £540.00 670g -5℃
Minimalist design cuts weight, but not warmth. For lightweight camping, mountain marathons, trekking, or as a backup.
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.