Sigma Synthetic Jacket

A synthetic-insulated lightweight jacket. Primaloft Gold-fill to cope with cold, wet conditions. Long in body & sleeve to block out draughts. 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 / 23°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.
370g / 13oz
Sigma Synthetic Jacket

It's winter. Client is very, very cold despite wearing all her spare layers. Problem. I give her my PHD Sigma to put on. Client gets warm. No problem.
Tony Halliwell (MIC).



  • Primaloft Gold® synthetic insulation (100gsm)
  • Breathable & windproof MX 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)
  • 1 zipped chest level pocket (insulated)
  • Lycra hem & cuffs
  • Stuff sac
  • Pack size: 13 x 21cm*
  • Options:
    • Wind and Water resistant Ultrashell outer fabric: adds approx 16grms (0.5oz) to weight. Available in: Burnt Orange, Blue, Charcoal, Red, Black, Green, Purple, and Gold.
    • Stud-on Primaloft Gold® filled-hood

*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.

Redesigned with longer body length, an insulated chest pocket, and more colour options.

With a combination of Primaloft Gold® insulation, our lightweight MX 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.

The Sigma Jacket 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 winter bike rides or icy mountain climbs, where your arms are extended. 

Zipped hand-warmer pockets at the waist provide a superb refuge for chilled hands and the zipped & insulated chest pocket is useful for stashing a GPS. The optional hood provides superb warmth and wind-block.

As with all our Sigma gear, this jacket uses high performance 100g Primaloft Gold synthetic insulation, edge-stitched for maximum loft and therefore maximum warmth.

In our experience the 100gsm Primaloft Gold® synthetic insulation absorbs water much more slowly than other synthetic waddings, a marked advantage in cold, wet conditions.

Optional Ultrashell Outer

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.

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

Some of these comments are for the Sigma pullover, which this Jacket replaces.

"Warm. Perfect fit. Arms even better fit. Total mobility. Instant loft like a down jacket. The Hood saved me from having to buy a down hat to sleep in. Quality stuff."
Tony Swallow.

"It's winter. Client is very, very cold despite wearing all her spare layers. Problem. I give her my PHD Sigma to put on. Client gets warm. No problem. Yours, thankful for the incredible performance from your nanogram gear."
Tony Halliwell (MIC).

"Very warm for its weight. Reasonably small pack size. The armholes are bound by lycra to give a close fit, as are the pockets. Small, but very nice detail."
Ross Evans on Outdoorsmagic Forum.

"Just a quick note to say after a month or so deciding which smock to buy, PHD, RAB etc. I plumbed for the Sigma and how happy I am with it. I can't wait to test it but if it performs as well as it looks and is made, which I'm sure it will, then I will be very happy."

"The Sigma pullover has arrived, and like everything else I have had from you is excellent."

"Not a query; rather a big thank you. Received today my Sigma pullover. Mightily impressed by the materials, build quality, light weight, compactness and elegantly simple design. I also have a Sigma vest in a larger size which fits into the top pocket of my rucksack and is so quick and easy to slip on at winter belays."

"Many thanks for my Sigma pullover which arrived yesterday ... I have been unable to take it off this morning - walking across the fields in below freezing frosty conditions, then cycling into town to do some shopping. I have been toasty warm with just a shirt underneath, and it makes me feel like a million dollars. It is so well made and thought out - I have just discovered the zipped security pocket - what a brilliant touch! It was meant to be Christmas present from my wife - but she is away at the moment and I just couldn't wait to use it. A fantastic start to Christmas!"

"Today I've received the Sigma jacket and I am very, very pleased with it - (roll on winter because this is so lightweight it's unbelievable)."

"Thanks for the two Sigma Pullovers. The pullovers were Xmas presents, and went down very well. They wouldn't take them off!!"

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