At 560g the Xeron can compete with all but the lightest of down jackets and compresses well for carrying. Very much in the modern style the jacket uses a combination of two distinct fabrics in different parts of the body; concentrating on keeping the core warm without reducing flexibility in the arms and shoulders.
What Mammut say:
Built for alpine activity, Mammut's Xeron Jacket is made using Pertex Endurance fabric with their Ajungilak OTI Climate fill insulation, which makes it lightweight, tough, breathable and water-repellent.
2 raised zip secure fleece-lined handwarmer pockets
Zipped chest pocket
Drawcord waist adjustment
Hook & loop cuff adjusters
2 way front zip, ideal when wearing a pack or harness
Mammut Xeron on test:
The Xeron jacket from Mammut has been on countless trips with me into the hills for Autumn and Winter 2016/17. I'm a big fan of synthetic jackets, due to spending most of my time in the damp hills and mountains of the UK, where keeping down wear dry on the move is nigh on impossible, be it from sweat or the elements.
The Xeron is a classic belay jacket and the sizing is perfect for throwing the jacket over your existing kit for the day, when you stop or when wind exposure gets too much. I have worn it under a hard-shell in mid-winter and as a standalone mid/outer as Spring makes an entrance, and although I enjoyed the warmth I found it a bit sweaty upon exerting in climbs and moving quickly. The Ajungilak OTI lining is just too warm for this in the main and in winter I prefer a lighter mid layer such as a Prism. That said, once you do get clammy, the synthetic fill keeps working and unlike down, offers greater insulation at compression spots like your elbows. If conditions are cold and dry the jacket is great as a windproof layer. If it rains, I have relied on the water repellent material for a while, but it will let wind driven rain in relatively quickly as I expected.
It is very packable and compresses nicely, with none of the usual concerns about repeatedly squashing your prized down jacket. The helmet compatible hood works well, although I find the peak in all but the harshest conditions a bit over generous. Unlike most hoods marketed as "helmet compatible" the Xeron's hood is designed to be compatible under the helmet rather than over it with full three way adjustment. This gives the advantage of adding extra head insulation for alpine use.
The two fleece lined hand warmer pockets are raised for easy access when using a harness or carrying a pack although they're perhaps a little on the small side - particularly if you want a map handy. The chest pocket is again easily accessible. The combination of Pertex Endurance for the shoulders and sleeves with Pertex Quantum for the main body, both DWR coated, both protect the heavy-wear areas and provide enough water repellence to allow you time to add an outer shell when the weather does take a turn for the worse.
Overall a good quality jacket that gives a lot of 'bang for your buck', currently priced at around £100 online. The Xeron has so far proved to be a hard wearing addition to my pack on low level walks or full winter conditions and suits climbers, hill walkers and mountaineers.