Montane Prism jacket Prism jacket Montane

Montane Prism jacket review

Posted by Sam Harrison on at 19:05.

 Gear reviews

alpine mountaineering alps bivvy climbing insulated jacket montane primaloft prism

One of the most versatile pieces of kit I own, I'm rarely without this lightweight insulated jacket which balances warmth against weight to near perfection.
Brand & model Montane Prism jacket
Good points  versatility, durability, warmth-to-weight ratio, well thought out design
 Bad points  a bit short
Best uses Everything! Alpine starts, standing around on belay ledges, emergency layer, summer bivvying, going to the pub, etc.

The Prism is a lightweight insulated jacket, boasting 40gsm of Primaloft Eco encased in Pertex Microlight to keep the wind at bay. It has less insulation and is therefore colder than its heavy-weight counterparts, such as the Rab Generator Alpine or the Montane Flux, but of course this means it is less bulky. As an over-generalisation, I'd say the jacket is ideal warmth for throwing on over your t-shirt at belay stances or when you stop for lunch during the summer, or using as part of a layering system (it being the outer layer if it's dry) for the coldest of winter days or early-morning Alpine starts.


There is little to distinguish between this and similar lightweight insulated jacket with the same amount of Primaloft; put simply, it's as warm as you'd expect it to be. It's not going to be as warm as a down jacket of the same weight, but then you don't have to worry about getting it wet like you do with down. I picture it as being warmer than a thick fleece but colder than a heavier weight insulated jacket, and actually it's this balance that makes the jacket a winner for me; it's the perfect warmth to make it incredibly versatile. As I've already hinted, there's never a season when the jacket isn't in my bag.


Top marks for durability, mainly thanks to the Pertex Microlight material it's encased in. My jacket has had some serious use, including a fair share of scraping against gritstone and hacking through thistles, and apart from the odd dirty mark, it looks brand new.


The jacket has two "hand warmer" chest pockets which are large enough to fit most useful things in (e.g. compact camera, map, pair of gloves). Being insulated, they're also incredibly useful in keeping your hands warm on chilly days, and they're positioned such that they're still accessible with a waist belt done up or with a harness on.

The hood is surprisingly good and being insulated, is perfect for keeping your ears and neck toasty warm on the coldest of days; indeed, it's a good "secondary" hood in full on winter conditions when you've got your waterproof jacket's hood up over the top of it. It's quite a snug fit and therefore it stays on your head better than most (two easy-to-use drawstring adjusters ensure this), though that does mean it struggles to go over a helmet. It won't give you the protection a proper hood on a waterproof jacket will, but it's a nice addition to compliment your layering system nonetheless.

There are a number of little reflective strips on the jacket, which you might think at first are just for show, but actually prove incredibly useful to others following you in the dark. Another feature I'm a fan of is the elasticated cuffs, which mean you didn't have to faff about tightening and un-tightening them every time you put the jacket on (though it does mean it's a bit of a struggle to put the jacket on with bulky gloves or mitts on).


Whether or not the jacket fits you is a personal choice, but I'll add a few general comments in case you're not going to have chance to try the jacket on before buying. The fit is usefully generous; I'm usually a standard size small, and a size small Prism allows me to fit a few of extra layers underneath. To me, the jacket feels quite "wide" (i.e. it has a large chest), whilst being short in length - I suspect this is to accommodate extra layers whilst retaining an "active" fit, but I do think it is a bit on the short side (I'm of average height; 5' 11''). As such, it does have a tendancy to ride up a bit when worn with a harness, but I'm being picky here and it's not a huge issue.

Weight and packability

According to Montane, a size medium is 418g and my size small is 385g; so, lighter than a lot of waterproofs and even fleeces. It packs away comfortably into its pocket (not like Rab jackets which are infuriatingly difficult to squeeze into their pockets and stuff sacs), but most of the time I just throw it in my bag and let the of the contents squash it down. Its weight and packability is similar to other lightweight insulated jackets with the same amount of insulation, and it's this balance between weight/packability and warmth that make the jacket so versatile.


The Prism is undoubtedly one of the most versatile pieces of kit that I own. It's surprisingly durable and has a number of useful features such as large chest pockets and elasticated cuffs. My only slight issue is that it's a bit short in length, but given all of it's other merits, this doesn't matter at all. Highly recommended and I promise you won't regret buying one!
Perfect for chilly early morning Alpine starts!
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