I’m always looking for thinner “top coat” layers that have broad temperature range and a bit of windproofing. This especially when I’m in a “fit” phase of my yearly cycle, moving faster and producing more body heat. Mountain Equipment’s Ultratherm jacket fits the bill.
Massing at 9.9 oz (280 gr) size large, Ultraherm is essentially a well constructed layer of windproof nylon with a bit of waffle shaped insulation laminated to the inside. Stretch panels on the sides add to the relaxed but still athletic fit. No pit zips, only one pocket (which doubles as a storage sack for the jacket), useful but minimal hood stows nicely in collar. Less is more.
I must have worn this piece at least 100 days now and it’s held up well overall. I’m only seeing a tiny bit of wear in the laminated waffle lining where it rubs under my backpack and shoulder straps. Small glitch in my pre-production tester was a weak welded seam that Mountain Equipment tells me is now strongly stitched. No worries there, but I mention because welded seams are cool yet should always be tested before you head off into the wild. Only change I’d make is to have thumb holes in the cuffs (which are also nicely minimalist, by the way).
Note that the Ultratherm nylon shell fabric is by intent a combination of breathability and wind resistance. Thus, any sort of waterproof membrane construction isn’t appropriate. I wore the Ultratherm in a lot of wet snowfall as well as a few rain drizzles. At this point in the wear cycle mine is not by any means even faintly water resistant, meaning it’s a good layer for dryer climates or days, but will turn into a wet nylon sheath if you try using it in damper precip conditions. For that type of layering I prefer leaving the non-waterproof nylon at home and instead using straight fleece under a membrain shell (or as a top layer that gets slightly damp but dries quickly). Again, this is all as it should be, not a detriment.
Continuing that thought, it would be cool to have this exact same piece only made with the lightest most pliable membrain fabric they could find. The idea would be to still have the breathable stretch panels under the arms and down the sides, along with lightweight insulation laminated to the nylon parts. Forgive my running on at the mind.
At any rate, if you’re looking for lightweight functional layers, recommended. Makes a decent cycling and hiking jacket as well.