We put all functional underwear in this category, such as shorts and short-sleeved T-shirts, as well as boxers or women's bras. We recommend orienting the material from which the clothes are sewn or knitted. If you are going to Mongolia or for a long trek, we recommend Merino wool, but if you are a speed hiker or fitness ski alpinist, we recommend synthetic lightweight fast-drying underwear. If you go skiing on a glacier or you only have thin pants, we recommend warmer fleece underpants.