When Mammut launched their new IS range of light clothing (bizarrely, they call it the IN range on their website), I was keen to call in some products for review, and left it to them to decide what to send.

A few days later a bright red and yellow Runbold Light IS Jacket arrived in the post. I’ve worn it a lot over the summer. Often for days out hillwalking and instructing, but more frequently for long days on the crags when rock climbing or scrambling.


It packs away neatly into one of the side pockets, and so can be clipped out of the way on the back of a harness which I really love.


The Runbold Light IS is also reversible, which is a nice touch, but so far I’ve not been brave enough to wear the lemon yellow as an outer, but the red side is a better option I think anyway.


On the plus side, this really is a very, very lightweight insulation layer, weighing in at just 292g. It’s also excellent as a warmth layer, being filled with 40 g / m² Primaloft Silver, and I have found it invaluable as summer moves into autumn for colder days out on the cliffs.

The cuffs are elasticated, as is the hem, and there are three zipped pockets, two as hand-warmer pockets, the other as an internal chest pocket. The hand-warmer pockets are too low to be used when wearing a climbing harness, but to be fair Mammut don’t market this insulation jacket as for climbing – it’s intended use is for hiking and mountain walking.

My only other remark is to say that the collar is getting a bit furry from my occasionally unshaven chin, but that’s as much a comment on my own scruffiness than anything to do with the jacket.

Overall I think this is a great insulation layer for those wanting something lightweight as a good alternative to wearing a down-filled jacket. It retails for around £185, so it’s not the cheapest on the market, but still very good value for a jacket of this quality.

For further details go to Mammut Runbold Light IS Jacket