The Mammut Aconcagua Pro ML is a midlayer intended for a multitude of outdoor activities, of course dominated by those involving spending time in the mountains. Alpinism, climbing and hiking are among those to which this jacket is suited best. Utilising Polartec’s Powerstretch Pro material, the Aconcagua Pro ML is touted to provide warmth, breathability and a more resilient stretch over other stretch fabrics. Having been used over a number of trips, this midlayer from Mammut performed very well on the whole but with a few minor niggles.
The first thing about the Mammut Aconcagua Pro ML, is its low weight and bulk. When compared to the Rab Powerstretch Pro Hoody not only does it weigh just over 100g less but it seems to pack down smaller too. With that said, the Aconcagua Pro ML is a little more minimalist at first glance, which can be seen as beneficial. There are no hood adjustments as found on the Rab Powerstretch pro, but this is likely down to how tight fitting the hood is designed to be. For the most part, I find a beanie hat to be more more useful and less restrictive which makes a bulky hood somewhat redundant on a midlayer such as this that is at its best when you’re on the move and just need to take the edge off in lower temperatures. That’s not to say that the hood is useless – it would be more comfortable under a climbing helmet than a beanie, for example. On the other hand though, and another plus point for the Aconcagua Pro ML, it does come with a napoleon pocket on one side which is a good size for keeping hold of anything you need close to hand such as a compass. It seems though, that the main saving in weight is down to the cut.
The only real gripe with the Aconcagua Pro ML, is its spartan cut. Yes, it is designed largely as an alpine piece but even with that in mind – this is the most close fitting midlayer garment that I have used. It is to the degree that the zip is impossible to close fully when the hood is up and does annoy a little due to how ‘clingy’ it is. There are short comings in the length also, as the waist hem hovers slightly below trouser waist bands. It would probably be wise to size up, unless you were to try the Aconcagua Pro ML on before purchasing.
Despite that, when in use, the Aconcagua Pro ML doesn’t really ride up much at all. The stretch in Polartec’s Powerstretch Pro means that although tight fitting, the fleece still moves with your body as you reach or stretch. It simply remains body hugging. Thumb loops at the ends of the sleeves do aid in this, but it is certainly a strong feature in a midlayer that will be used when climbing or scrambling. The thumbloops help with keeping the wind out and your wrists warm very well, too. As is described by Polartec of its Powerstretch Pro material, the Aconcagua Pro ML does spring back into its original shape and size no matter how long or hard a wearing it has had. After a three day trip, the jacket was as snug as when new. This is certainly sure to stop the frustration of cold winds finding their way up the sleeves or in through the bottom of the jacket when climbing, scrambling, or trekking – even on multiday trips. Another benefit to the cut of the jacket, or more specifically, its inherent low weight and bulk is the ease at which it can be put in a rucksack and forgotten about over the course of longer and more intensive activity if needs be.
For the weight, the Aconcagua Pro ML actually provides a good amount of warmth. Protecting against the cold on a recent trip to Snowdonia where temperatures were around 5c and below while gaining height, scrambling on the Carneddau range. When coupled with a windproof layer, it created a great layering system with a thin baselayer underneath. Even on its own, there does seem to be a bit of wind protection although it is not something advertised by Mammut or Polartec. The construction of the jacket helps here in that there are two types of fleece to this jacket with the yellow sections (on this particular colour scheme) have a nicely brushed backing, while the blue sections follow a waffle grid pattern. The trapping of warm air as a result of this is greater than a standard fleece and it certainly noticeable when looking at how thin the Aconcagua Pro ML is in actuality. The grid pattern also aids in the wicking of moisture away from the body – further adding to the comfort achieved in wearing this jacket.
There are all the usual extra touches found on the Mammut Aconcagua Pro ML that you would expect on a top outdoor garment; flat lock stitching situated off the shoulders, thumbloops, glove compatible zip pulls. It’s easy to say that these features tie in well with the level of performance found with this fleece. One final thing that Polartec mention about Powerstretch Pro is its durability, “The outer surface has a low-friction finish to reduce irritation when worn with other fabrics and increase overall abrasion resistance. This next-to-skin layer stays dry, breathable and comfortable by continuously transferring moisture vapor for rapid evaporation.” Going forward, it should be seen just how true this is alongside the retention of shape achieved by the four way stretch fabric.
Overall, this is an impressive midlayer for mild and colder temperatures, the annoyance of just how tight-fit it is really does do the rest of the positives of the Mammut Aconcagua Pro ML, a disservice. Try on or size up to get this right, and you do have a great fleece jacket.
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