Zeta 2 Primaloft Sleeping Bag

Specialised Primaloft-filled bag for climbers' bivouacs in damp conditions. Reliable comfort on an overnight belay ledge.
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.
-20°C / -4°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.
1120g / 40oz
Zeta 2 Primaloft Sleeping Bag

Last week I climbed the North Face of the Eiger ... Both my self and my client used your Zeta sleeping bags. They were just fantastic and completely idiot proof.
Mark Seaton.



  • Outer Fabric: water-resistant Ultrashell
  • Inner fabric: super-light MX
  • Synthetic Primaloft Gold insulation, edge-stitched for maximum loft
  • Twin 2-way zips at front for access and for armholes for cooking etc.
  • Large inside chest pocket
  • Stuff sac with clip loop
  • Pack size: 23 x 40cm
  • Reflector strips for night location
  • Clip-loop for securing
  • Hood draws up close around head
  • Footpiece: ovoid shape fits naturally to feet
  • Colour: Blue
  • Options:
    • Deep overhead insulated cowl-cover in waterproof Dri-LX fabric (+250g/+£110) (same colour as chosen fabric)
    • Taped outer shell in waterproof Dri-LX fabric (+250g/+£185) (red, white, black, green)
    • No (twin front) zips (-60gr/-£30)
    • Full-length zip (no twin zips) (+30gr/£41)
    • Short or Long lengths
    • Slim or Wide widths

†Please note: We make our stuff sacs big enough to allow fairly easy stuffing rather than reducing the bags to the tightest minimum.

‡Please note: The optional waterproof Dri-LX outer provides an extra seam-sealed outer shell to the bag. While a shelled sleeping bag is not designed to be used alone in heavy rain (the hood area is open to the elements) the shell does protect the bag when it is used outdoors without a tent.


Recently redesigned

Updated with Primaloft Gold filling and a greater range of build options, the redesigned Zeta 2 synthetic sleeping bag is now 35% lighter and more compressible than before. The new, taped water-proof Dri-LX shell and insulated overhead cowl options boost the bag’s performance in extreme conditions.

Combine with the Zeta Overbag to extend the use of this specialist bag from -20°C to -40°C.


Designed specifically for climbers' bivouacs in damp conditions, with all the advantages of Primaloft-Gold synthetic fill and water-resistant Ultrashell outer fabric. The twin front zips, an extra bivvy feature, double as arm holes for cooking and gear sorting. The large inside chest pocket keeps stashed kit warm. An optional insulated cowl cover (in Dri-LX fabric) sheds snow. The reflective strip and clip loop confirm this bag is one for climbers in extreme situations.

The optional waterproof Dri-LX outer provides an extra seam-sealed outer shell to the bag.

Read our technical briefing on down vs synthetic insulation.


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.

Ultrashell (weight: 40 gsm)

One of the lightest of PHD's coated materials. This ripstop nylon provides complete wind block and good water resistance at minimal weight. Ultrashell gives an excellent upgrade to performance with very little weight penalty.

Superlight MX fabric (weight: 32 gsm)

A mini-ripstop nylon with excellent tear strength, MX is the pick of the superfine 15 denier downproof materials. We have tested lighter fabrics, but most have had significant drawbacks, while our confidence in MX is based on several years of extensive use in both our ultralight and our high mountain gear.

Primaloft Gold®

Primaloft Gold® is the ideal microfibre insulation. Ultrafine fibres produce an insulating core that is incredibly soft, lightweight and water resistant. In our experience it absorbs water much more slowly than other waddings, a marked advantage in wet-cold conditions.

The nearest of the synthetics to the feel of down, yet tougher than you would expect. Primaloft Gold® offers the best warmth/weight performance in the Primaloft range

Review is for previous version of this bag

"Last week I climbed the North Face of the Eiger ... only the 2nd time a British Guide has done this. We had two bivys on the face and one on the summit. Conditions were difficult and we wore crampons for the entire route. Both my self and my client used your Zeta 2 sleeping bags. They were just fantastic and completely idiot proof. "
Mark Seaton.

Works well with
From £164.00 150g
Primaloft-filled mountaineering mitts. Confidence and warmth in cold and wet conditions.
From £534.00 870g -4℃
Used in combination with your Zeta bag to boost its warmth by 24°C. This...
From £558.00 800g -20℃
A Primaloft insulated belay jacket for unfriendly wild & damp conditions. Designed...