First impression
The two sides in the larger areas (chest, sleeves and sides) of the shirt are equally striking. One side is rougher and therefore has a large surface area. If this side is worn on the inside, it is intended to increase insulation, while the large surface area on the outside allows sweat to evaporate quickly. The material on the back and under the armpits is thin and almost mesh-like. Only the undersides of the sleeves and the lowest part of the stomach and back are made of "normal" fabric. The sleeves are nice and long and have thumb loops.
Tester & test conditions
I am 183cm tall and weigh about 75kg. I'm wearing the Tuvegga shirt in size L. It fits well, but due to the stretchy material and the long sleeves, I could certainly wear a size M as well. But L doesn't hang loose on the body either, so that's a good size. I've been wearing this fine piece since the beginning of February and have worn it on most of my skiing days (sometimes even merino underwear has to be washed), so it's been used on ski tours, freeriding and piste skiing in a wide range of temperatures.