Gamma Synthetic Jacket

Our super-light synthetic-insulated jacket. Total wind block from our 7X fabric, and Primaloft Gold insulation to cope with cool and damp conditions. A superb windproof outer layer or an insulated mid-layer. 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.
5°C / 41°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.
240g / 8oz
Gamma Synthetic Jacket


  • Primaloft Gold® synthetic insulation (60gsm)
  • Breathable & windproof 7X outer and inner fabric
  • Long in body length
  • Edge-stitched for maximum loft and warmth
  • Full length lightweight front zip
  • Insulated under baffle with wrapover chin guard
  • 2 zipped hand warmer pockets at waist level (insulated)
  • Lycra hem & cuffs
  • Stuff sac
  • Pack size: 13 x 21cm*
  • Options:
    • Stud-on Primaloft Gold® filled-hood
    • XS, S, M, L, XL
    • Custom sizes

*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.

With a combination of Primaloft Gold® insulation, our super lightweight 7X fabric, light zips, and a simple design, this synthetic-filled Jacket is the right piece of kit when it's going to be cold and damp.

At just 240g (medium size) the ultra-light Gamma Jacket is a superb layer for long distance trekking, backpacking, and racing. The combination of total wind-proofness and synthetic insulation makes for a versatile jacket or mid-layer.

It is cut long in body to reduce cold air ingress around the lower back, and the long sleeve length offers superb protection during activities, like bike rides, where your arms are extended. 

Zipped hand-warmer pockets at the waist provide a superb refuge for chilled hands and the optional hood provides superb warmth and wind-block.

As with all our Gamma gear, this jacket uses high performance 60g Primaloft Gold synthetic insulation, edge-stitched for maximum loft and therefore maximum warmth.

In our experience the 60gsm Primaloft Gold® synthetic insulation absorbs water much more slowly than other synthetic waddings, a marked advantage in cold, wet conditions.

Ultralight 7X fabric (weight: 22 gsm)

7X is our new sheer-light 7 denier fabric. An exquisitely fine rip-stop nylon, 7X is incredibly light, highly wind-resistant and has first-rate down proofing. This fabric helps us create the very lightest of gear in the PHD range. Of course the lighter the fabric the lighter the sleeping bag or down clothing, and the less space it takes up in your rucksack. This fabric is so light it actually helps to allow even greater lofting of the down too.

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

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