Zeta Belay Jacket

A Primaloft insulated belay jacket for unfriendly wild & damp conditions. Designed especially for tough climbing days on classic mixed mountain routes and technical steep water-ice. Now also available in custom sizes.
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.
800g / 28oz
Zeta Belay Jacket

Perhaps the best belay jacket on the market ... close to perfect.
Andy Kirkpatrick.



  • Outer fabric: Waterproof / Breathable HS2 outer fabric* (with taped shoulder seams)
  • Inner Fabric: Breathable ripstop superlight MX
  • Primaloft Gold® synthetic insulation (200g/m weight in body and sleeves)
  • Shoulder seams taped
  • Front closure - 2 way YKK Aquaguard water-resistant zip with bottom locking stud
  • 3 insulated pockets:
    • 2 zipped waist level pockets
    • 1 zipped chest pocket
  • Integral hood with wired peak, sized for a modern climber's helmet:
    • Adjustable front cord with cord ends tethered inside the hood
    • Wired peak
    • Volume reducer on the back of the hood
  • Reflector tape on front and back for night location
  • Clip loop to secure jacket at change-overs
  • Double exit adjustable hem cord
  • The Primaloft filling is edge stitched only to allow maximum loft
  • Cuffs; simple Velcro closure, to go over or under gloves
  • Stuff sac
  • Pack size: 17 x 28cm**


*Please note: Please note: although the outer fabric is waterproof, only the shoulder stitch lines are taped. So, although the outer will shed a lot of rain and snow, in a heavy downpour water can penetrate the stitching. However, the Primaloft Gold insulation retains much of its insulation if wet. As always in the mountains, if there is a possibility of prolonged rain, carry full specification waterproofs.

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


Also available in custom sizes. We make clothing to order, so if you’re not a standard size we can make it to fit. To order a non-standard custom size, select the Custom Sizing tab, choose your body width, and then the body/arm lengths, shorter or longer, that work for you. A custom size takes us a little longer (typically two weeks longer) to make and, because it’s personalized, it’s non-returnable and our customer loyalty scheme can’t be applied.

Part of PHD’s collection of synthetic filled Belay Jackets (the BetaEpsilonAlpha and Zeta, with TOT* ratings of -5°C /-10°C /-20°C respectively), these technical insulating tops are perfectly adapted to wild, wet, unforgiving conditions: typical Scottish winter, essentially. It doesn’t end there though: demanding routes in demanding conditions – whether on steep water ice, big mountain faces or classic mixed test-pieces – are where these jackets belong, and those conditions will be familiar to climbers throughout Scandinavia, the Alps, the Arctic and Patagonia.

Equally at home when climbing or on the belay ledge, if you choose to swap one jacket between two of you as you change over at belays, you’ll find the cut is roomy enough to fit over your outer layers. If you’re keeping it for yourself though and climbing in it all day, the fit is nevertheless trim and efficient: ideal for wearing under your harness.

Freedom of movement is essential for a climber’s jacket, and so of course is protection from the elements. The climber-specific fit, waterproof fabric (with taped shoulder seams), grown on hood, full length water-resistant zip, extra body length, and pocket locations make for a solid, dependable jacket which allows you to just get on with the task at hand. These features are repeated throughout the collection, and with different levels of warmth to choose from, these belay jackets prepare you for a vast range of winter climbing adventures.

The collection share the same feature list but have different thickness of Primaloft insulation:


Weight of
Primaloft Gold

Beta Belay 60g/m2 0°C
Epsilon Belay 100g/m2 -5°C
Alpha Belay 133g/m2 -10°C
Zeta Belay 200g/m2 -20°C


In our experience Primaloft Gold® absorbs water much more slowly than other waddings, a marked advantage in wet-cold conditions. Effectively, if you can retain warm air in the insulation rather than it being replaced by cold water the garment will stay much warmer.

Please note: this jacket is designed and sized to be worn over top / outer layers. It provides additional warmth on cold belays and can be swapped between climbers at pitch change-overs. If you want a trimmer more athletic fit select the next size down

*TOT: Typical Operating Temperature

As used by Ian Parnell and Andy Kirkpatrick.

Outdoor photography by Paul Horsman.

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

Waterproof HS2 outer fabric (weight: 88 gsm)

HS2 is a 2-layer laminate, a high-spec option for the outer layer of our insulated gear. This ripstop fabric strikes an excellent balance between lightness and durability. It is light enough for our Belay tops and tough enough for expedition use in our Omega clothing, while the Kappa clothing makes full use of both its qualities. HS2 is completely waterproof (when the seams are taped) and offers excellent breathability. (Weight: 88gsm).

"Best coat ever! Thank you so much"

Reviews relate to the previous version of this jacket

"Perhaps the best belay jacket on the market ... close to perfect in weight, bulk and features ... a lot of top climbers bought the jacket, even though many were sponsored by other companies."
Andy Kirkpatrick.

"I must say what a great bit of kit it is too, either inside or over the top of my wind suit while waiting on the belay (as we did for one session of 2 hours at 5700m+) it proved to be a winner every time - I'd recommend it any time."
Paul Collin (attempt on Chek-igo, Nepal).

"I ordered a ... Zeta Belay Jacket off you guys middle of last year. I used [it] on Cho Oyu and [it] worked fantastically ... I did put the gear through a thorough test and am totally happy with the way [it] performed."
Ben Kane

"My Mt. Rainier climb was a great success and your jacket was perfect."
John J. Fernandez.

"I have used PHD clothing in the Alps and Caucasus and I have grown to trust the performance and the quality that they offer. The Zeta belay jacket especially has been a life saver a couple of times!"
Robert Gatt, team member Challenge 8000.

"My Zeta Belay Jacket is great insurance for damp times on the Polar ice."
Adrian McCallum, Scott Polar Research Institute.

"A brilliant jacket."
Nick R.

"I couldn't think of a better jacket for Scottish Winter, avoid the worry over down getting wet and get a synthetic like this. It has obviously had lots of thought into the design as everything seems to be perfectly suited to climbing."
Steve Sharland on Outdoorsmagic Forum.

"I have a PHD Zeta. I like it. It seems to have all the right things in all the right places, and it's jolly cosy. I like the handwarmer pockets."

"My first PHD product and I'm extremely impressed, just throw it on at stance or when stopped on the hill, over everything wet or dry. Great. Has a rugged feel to it compared to down which I always find very fragile."

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