Mammut Masao Light HS Jacket Review


For gnarly winter days, or when using a waterproof jacket while climbing abrasive rock, a heavier weight fabric is optimum. However, for all other circumstances a lighter weight garment will always be preferred.  Light weight always equates to thinner, and thinner means more packable and more comfortable.  It is the type of hardshell I use for at least 3/4 of the year.  The Mammut Masao Light HS is a new offering in this category, and I have been testing one out in the ‘changeable’ (aka wet!) conditions of British summer 2019.


The Masao Light HS is constructed from Mammut’s DRY Technology Performance fabric.  This is a  24,000mm vapour permeability fabric with 20,000mm hydrostatic head.  I’ll explain this a bit more later, but in simple terms it means it has a high level of waterproofness and is breathable enough for aerobic activities. Oh, and I’ll explain this later as well, but the jacket features a PFC free Durable Water Repellant (DWR) coating.    

The fabric is at the mid to lighter end of the market for waterproof fabrics and with the stripped features of the Masao Light HS, you are getting a full jacket in a pack friendly weight of 233 grams. Not so light that it isn’t durable enough for full on use in varied conditions, but light enough to tuck away in the bottom of your pack without thinking it will weigh you down.  

Of those stripped back features, the Jacket has everything you need without extra unneeded bells and whistles.  The hood is helmet compatible and includes a stiffened wire peak, an inner elasticated gusset and a drawcord closure.  

The full length front zip is a waterproof Aquaguard model and there are 2 zippered side pockets set high enough to be away from a pack waistbelt.  A third Napoleon style chest pocket completes the storage options.  

Mammut have used added simple elasticated cuff closures and a drawcord hem.  Lastly, and quite unusually for a lightweight hard shell of this type, there are underarm pit zips.  Mammut make the jacket in 6 colours and the one tested was a rich blue colour called Poseidon. The Masao Light HS retails for £249.

In Use

The Masao Light HS is a very good looking jacket with subtle and yet stylish design.  The colour I was sent for review is a deep and rich blue which looks great.  The logos are subtle and the shaping is excellent.  I would say that the jacket sizing, described as athletic, is certainly on the snug side when compared to some other brands.  I pretty much always fit a medium and, although this fits fine, it is definitely less roomy than other jackets I’ve used recently.  Just something to bear in mind if you are looking to buy online.  

That slim fit is very likely to also be intentional. Mammut market that Masao Light HS as a garment for a range of mountain goers and the addition of features like the shaped hood and pre shaped sleeves match the trim fit as a garment for Alpinists just as much as hill walkers. 

Mammut, of course, make garments in a broad range of materials including, as in this case, a home brand version called DRY Techology Performance fabric.  I have used home brand materials from a range of manufacturers and the reality is that they often perform just as well as ‘branded’ fabrics.  The advantage for brands is that often, as there are no big licence fees to pay, they can produce garments at lower cost.

In the case of this fabric Mammut state a 20,000mm hydrostatic head which is, if you aren’t familiar, a standard measure of waterproofness. It relates to how much height of a column of water a garment can withstand before liquid begins to penetrate through the material. In the UK manufacturers are allowed to claim a fabric is waterproof with a hydrostatic head as low as 1500mm, but most good quality waterproof materials comfortably exceed with figures of up to 30,000mm easily available. At 20,000mm, the jacket will offer a very good level of waterproofness and this has certainly been the case in tests so far.  

Remember also that a waterproof is subjected to a lot of wear as rucksack straps and waistbelts rub across it and so manufacturers also add a Durable Water Repellent (DWR) coating to minimise  water beading up on the surface.  Traditionally, manufacturers have used DWR coatings containing polyflourinated or fluorocarbon (PFC) compounds but, given the overwhelming scientific evidence that they are environmentally damaging, it is great to see a growing trend by manufacturers to use PFC free alternatives.  Well done to Mammut for being a leading player in this and the Masao Light HS is another of their products featuring a PFC free DWR coating.

Along with waterproofness, the other essential consideration when choosing a hard shell is the fabric’s breathability.  Mammut quote a vapour permeability of 24,000mm for this material and this stacks right up there against products like Goretex Pro with a vapour transmission rate of 25,000.  Of course, there are lots of factors affecting how well a garment transfers moisture, but I have found the Masao Light HS to perform really well.  It recently accompanied me on a damp (at times) trip to the Triglav National Park in Slovenia and, as there was a group of us with jackets from various manufacturers, I was able to do a direct comparison (which usually involved me sticking my hand inside their jacket after a steep ascent!) and it certainly stacked up extremely well against the fabrics of competing brands. 

Finally, other things that will affect a garments waterproofness include zips and other design features.  Mammut have obviously fully seam sealed the Masao and have included a waterproof Aquaguard front zip.  In my experience these can become less waterproof over time, but certainly the zip has stood up to everything thrown at it so far and is certainly looking as good as new. It is also worth mentioning nice details like a chin/beard guard which I certainly consider a must have on any quality jacket – they are one of those things that you don’t notice until you don’t have one! 

The pockets are well thought out.  The twin side pockets, which close with waterproof zippers, are placed high enough so that you can use them when wearing a harness and they can be used as handwarmer pockets if needed.  It is worth saying that I never, even if they feature waterproof zips, never actually consider pockets waterproof. But, that said, these certainly do a good job of protecting whatever is inside.  

The reality for me is that I rarely use pockets at the side of a jacket like this – I would rather have chest pockets.  In this case the Masao has one chest pocket that I have found to be great for smaller items like a phone, compass or snacks.  

Lastly, while discussing zips, Mammut have included pit zips on this jacket.  I must say that I never use pit zips and would happily never have them on any jacket.  I find them unnecessary if the jacket fabric breathes well enough.  Having said that, I know a lot of people love them and so, if they are your thing, you’ll be delighted that Mammut have featured them. 

The hood fits well and I have found it comfortable when pulled over a low profile climbing helmet. I wouldn’t say it is over generous on size though, so do consider that if you have a bulky lid.  Everything else about the hood works as expected – it zips up nice and high around the chin, the volume adjuster works well and the drawcord snugs it nicely when the winds whip up.  I also always consider a stiffened peak to be another essential and so well done again to Mammut for including one here.  

Lastly, I should also mention the simple elasticated cuff closures. In a world of complex design, having a jacket with simple and yet functional cuffs is very refreshing.  Similarly, the hem drawcord is also simple, functional and yet uncluttered.  Every feature the Masao has works well, and yet Mammut haven’t weighed it down with stuff you don’t need.  Well done Mammut.  


In a marketplace where a hard shell can easily cost £350-400, it is really good to see some high quality and top performance products that are significantly cheaper.  The Masao Light HS, at an RRP of £249, represents excellent value and yet wants for nothing.  It will serve hillwalkers, mountaineers, skiers and any mountain goers wanting a light weight garment and I consider it another strong hit from Mammut.  More details are available on the Mammut website here.  

Tested and posted by Paul