Sleep systems

UK Camp – 3 Season: System 3

The Wafer gear will help to keep you warm around camp, then at night it joins the Filler bag as another booster inside the Ultra bag. The combination of these three down layers will give you a night-time performance of about -7°C, enough for most spring and autumn camps in the UK.
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.
-7°C / 19.4°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 Items:
      • Filler Down Sleeping Bag
      • Wafer Down Jacket
      • Wafer Down Trousers
      • Wafer Down Socks
  • Full System Sleep Rating: -7°C (19.4°F)


This highly versatile system will cope when spring or autumn nights suddenly turn colder, but it will also give you superb ultralight options across most of the year. 

Much of the time you will only need to carry one bag, either the Filler, which on its own is a super lightweight for the warmest nights, or the Ultra, which is a great summer all-rounder. 

For colder conditions combine the Ultra with the Filler or with the Wafer clothing. Then put all three together for full spring and autumn camping. 

This system allows you to make your own decisions on just how light you want to travel on each trip.

Review relates to Minim Ultra K Sleeping bag

"This is the smallest-packing, quality down sleeping bag I've seen. It fits into a jacket pocket. I've been as warm in this as I have been in bags twice the weight."
Trail Magazine.

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.

Review relates to Wafer Down Jacket

"Amazingly light … packs down into a tiny ball. It's very comfortable to wear. I took the Wafer on the Scottish Watershed and loved it on chilly nights."
TGO Magazine's Gear Editor, Chris Townsend. Read Chris' full review.

Review relates to Wafer Down Trousers

"I wore my wafer trousers for three days non stop … never climbed in such horrific weather and conditions."
Jon Griffith climbing Link Sar, Pakistan.

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.
From £457.00 190g 0℃
One of the lightest insulated jackets. A combination of an exceptionally lightweight fabric with PHD's unique 1000 fillpower down. A 'K Series' product: warmth to weight at the limit of possibilities.
From £403.00 130g 0℃
Our lightest insulated trousers. A combination of our lightest fabric with PHD's unique 1000 fillpower down. In stock: ships in 5 days.
From £199.00 45g
Boosts the performance of your ultralight sleeping bag. Warm feet from the tiniest package. Ships within 5 working days.