Montane's New Prism Jacket Review

© Dan Bailey

The updated Prism Jacket is a versatile light-to-midweight synthetic insulating layer that's suited to a wide range of uses and conditions, whether worn as a midlayer or on top. While the feature set is aimed very much at climbers, I've been using it equally this summer for mountain rock days, scrambling, camping, bivvying and general hillwalking. As an all-rounder, I think it's a great jacket at a very decent price.

Feeling glad I packed it on a windy summer bivvy  © Dan Bailey
Feeling glad I packed it on a windy summer bivvy
© Dan Bailey

So what's changed from the previous version of the Prism? There's nothing major, Montane tell me, but among the tweaks are: a closer, more athletic fit; zoned baffling around the chest; better zips; a new 'Featherlite' Mini Rip-Stop 20D lining; and use of 100% recycled PrimaLoft Silver Eco (same performance as the standard stuff, but better for the environment). I think all the little upgrades add up to an excellent jacket.

It has a good active cut for climbing  © Masa Sakano
It has a good active cut for climbing
© Masa Sakano

Keeping off the breeze, without overheating, on the Basteir Tooth  © Masa Sakano
Keeping off the breeze, without overheating, on the Basteir Tooth
© Masa Sakano


The new Prism has what the industry would call an 'active' cut, but not an extreme one, so while it feels slim and fitted enough to wear as a midlayer over just a T-shirt there's still room for a couple of bulkier layers underneath - I've worn it a lot over a long sleeve baselayer and thin fleece, for instance.

Jackets that are cut too short in the body are a bugbear of mine (perhaps I just have a long body) but the Prism is around mid-length in the hem, sitting just below my waist at the front and dropping lower at the rear to offer at least partial bum coverage. Thanks to its length there are no cold spots around the midriff, which I think helps the Prism feel relatively warm for its modest weight. The hem sits snugly under a harness, and a really effective articulated cut in the sleeves means that I've got practically no hem lift when raising my arms to climb. It is surprising how often hem lift is a problem in jackets that are nominally designed for climbing, but Montane have done a proper job with the tailoring here. There's room in the sleeves for a climber's forearms, and the cuffs can fit either over or under a glove (and can be pulled up to dump heat). Altogether it's a big tick on the fit.

It's proving a useful warm layer for hillwalking as well as climbing  © Dan Bailey
It's proving a useful warm layer for hillwalking as well as climbing
© Dan Bailey


I make the Prism 428g in a size Large, which puts it towards the light end of the midweight category, or perhaps the heavier end of lightweight. These lighter-middle-weight pieces are great on versatility, doing service either as your main jacket in spring/summer or as a winter midlayer. At that weight you can carry it just in case, even in high summer.


Inside you get 40g/m2 PrimaLoft Silver, a 100% recycled synthetic insulation that's good on warmth for weight and reasonably compressible when packing. It may not be PrimaLoft's class-leading Gold insulation, but for a jacket like the Prism I'm sure Silver is a perfectly decent choice, and no doubt helps keep things affordable. Having worn it a lot when on the move I'd say the Silver seems pretty breathable, and I've yet to get uncomfortably sweaty in the Prism. Its role as an active layer is also helped by the fact that 40g/m2 is simply a lot less insulation than you'll find in many midweight synthetic jackets.

Good synthetic insulation for sub-optimal weather  © Dan Bailey
Good synthetic insulation for sub-optimal weather
© Dan Bailey

But not too hot when the sun comes out  © Masa Sakano
But not too hot when the sun comes out
© Masa Sakano

It may be a cliche, but it's a cliche because it's true - decent synthetic insulation is going to be warmer than down when wet. It also takes more abuse. For wearing all day on rainy Munros, dank scrambles and soggy summer bivvies I'd choose the Prism over a similar weight of down jacket every time. Likewise, if you're picking a jacket to repeatedly stuff in the bottom of a crag pack or scrunch into a ball to hang off your harness, the Prism and its PrimaLoft fill are made to cope. I suspect it might be quite good as a winter climbing mid layer too, something I'll no doubt try this coming season.


Montane have used a 30D Pertex Quantum outer, which is tough for its weight. The fabric certainly seems breathable enough to me, and having worn it on a lot of breezy summits I'd say very windproof too. With a DWR treatment it shrugs off light moisture, but you will of course need to add a shell if it starts properly raining. After a few weeks of use, including climbing and scrambling days, the outer fabric still looks good as new.

Light fabric, chunky main zip, single chest pocket...   © UKC Gear
Light fabric, chunky main zip, single chest pocket...
© UKC Gear

The lining, meanwhile, is a lighter 20D nylon. This feels comfortably non-clammy on a bare arm, and its shiny finish slips easily over other layers. I only have one criticism of the fabric: the 'arbor green' colour scheme of my review jacket is an acquired taste (and one that I haven't acquired). Rest assured it also comes in a range of more tasteful and photo-friendly colours.


A climbing-oriented jacket lives or dies on the quality of its hood, and this one easily accommodates a bulky foam helmet. With the front zip undone head movement is not much restricted, but do the zip right up and it becomes difficult to look straight upwards. For climbing in the cold I might be more inclined to wear the hood under my helmet, which permits better mobility.

It's got a decent helmet-friendly hood  © Dan Bailey
It's got a decent helmet-friendly hood
© Dan Bailey

Of course even climbers aren't always going to be climbing, to say nothing of walkers, so it's vital that a hood also works on a helmet-free head. The Prism's is great in that regard, with three points of adjustment to bring the fit in close onto a bare head. Its fleece-lined collar feels snug against the skin and comes high enough to provide some chin protection. You also get a decent stiffened brim, which allows the hood to hold its shape without flapping in the wind.

Stashes into one of its pockets  © Dan Bailey
Stashes into one of its pockets
© Dan Bailey

The Prism has three zipped pockets, a decent-sized pair for the hands and a single smaller chest pocket (good for a smartphone). The hand pockets are positioned high enough to access when wearing a harness or rucksack hip belt, and one of them doubles as a storage pouch with a clip tab so you can hang the jacket off a gear loop.

The cuffs are simple elastic  © Dan Bailey
The cuffs are simple elastic
© Dan Bailey

In the interests of durability there's a chunky YKK Vislon main zip. If you were using the Prism as a belay jacket its single zipper might seem a small niggle; but as you'll probably be wearing this jacket under your harness more often than over it, I don't think it's a big issue. Hem drawcords and simple elasticated cuffs complete a very functional list of features.

Testing out the Prism on Am Basteir  © Masa Sakano
Testing out the Prism on Am Basteir
© Masa Sakano


With its excellent active cut and well-considered set of features, the Prism is a superb jacket at a price it's hard to argue with. If you're after a light synthetic insulated layer for climbing, walking or just general outdoor use, it really ticks all the boxes. I'm a big fan.

Montane say:

Prism prod shot  © Montane

A modern classic, the Prism Jacket balances warmth, weight and packability perfectly as a warm mid or outer layer for any fast and light mountain activity.

Using weather resistant PERTEX® QUANTUM, 100% recycled 40g/m2 PrimaLoft® Silver insulation and upgraded with a lightweight nylon lining; the Prism Jacket has a climbing helmet hood and good pocket options. Stuffing inside its hand pocket means it packs down small so it can be kept in your pack for a warm, windproof and weather resistant layer in almost any mountain weather.

  • 30 Denier PERTEX® QUANTUM outer with DWR
  • 40g/m2 PrimaLoft® Silver 100% recycled insulation
  • FEATHERLITE™ Mini Rip-stop 20D nylon lining
  • Fully adjustable roll-away insulated climbing helmet compatible hood with stiffened peak
  • Articulated arms for high reach movement
  • Full-length YKK VISLON® front zip with internal storm flap (two-way zip Alpine red only)
  • External chest pocket with YKK zip
  • Two insulated map-sized hand pockets with YKK zips
  • Low bulk elasticated cuffs
  • Adjustable hem with cinchable drawcord
  • Stuffs into the right-hand pocket with internal carabiner loop

For more info see

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20 Sep, 2019

It seems there is no topic for the associated article yet (I thought UKC's CMS autogenerates them, but perhaps not).

As I currently need to buy a new lightweight insulated synthetic, and the Prism is among the ones I looked at, what are your thoughts on 40g of primaloft vs 60g that is somewhat more commonly used?

Is it still inside the sweet spot for active insulation (a jacket one wears under harness all the time vs. a belay jacket), or a bit too low, for normal altitude mountains?

It uses just the normal Pertex Quantum, not the more breathable (and less windproof) Quantum Air, is that right? Is it still breathable enough?

And since synthetic fill usually tends to loose insulating power faster than down (though for an "active" jacket, down is out of the question here), I wonder if the 40g would be a bit on the low side after few outings and stuffings, making it effectively just 25g or so (perhaps exagerrating a bit, but hopefuly you get my meaning)?

Otherwise, the jacket is among the few I am considering (as the price is right as well, and the hood looks nice too) :)

Moderators, if you do create a dedicated forum post for the review in question, please move my post there, so we don't have doubles in the forums :) thank you!

Hi, seems there was an error in auto creating the thread this time! thanks for letting us know. I have moved your comment into this thread.


20 Sep, 2019

I have the previous version which doubles up the insulation in the body area around the pockets, giving 80gm of insulation. This works well. But I cant see it mentioned as having the same in the new model.

Hi Frank - glitch in the system, hopefully fixed now...

40g vs 60g+ ... To state the obvious, it's not as warm when you're stood about but on the other hand you aren't going to overheat as quickly when you're on the go. It's probably best regarded as a lightweight jacket, not a midweight. It's not an exact science since we all run differently, but I'd use it as a belay jacket in spring/autumn sort of weather, but definitely not in winter.

It seems a sensible amount of fill for active use - I've only worn it on summer hills so far, and not found it too hot when climbing in cool/breezy conditions although of course if you're steaming up a hill then most insulated jackets are going to be too hot, and this is no exception. I can see it being a good active layer for winter mountains though I'd be bringing a warm belay jacket too (would it be odd, taking two weights of synthetic jacket? jury's out)

Fabric. On paper Quantum Air would seem to make more sense in an active piece than Quantum, but I think the Quantum works well here as this is quite a multi-purpose jacket. So far it has seemed to strike a useful balance between wind resistance and breathability. I don't run particularly hot or cold, and I'm not a very sweaty person.

Durability of fill: I can't make any long term verdict yet but it's fine so far. Personally I'm a lot more precious about down jackets and much happier to mistreat synthetic ones. Yes the fibres do degrade over time/use, but I'm not sure how much this really affects the performance until things get noticeably thin and threadbare. I don't think you'll be feeling like it's down at the equivalent of 25g after only a few uses!

I actually hadn't noticed, and it's not in the product spec. But you may be right, just in the pocket area. I'll ask Montane

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