This base layer is made of a comfortable merino wool and polyester blend fabric. There is some minor pilling throughout (see photos 8 and 10, etc.). Please understand this before purchasing. It's a unisex XS size, but the fit is slightly relaxed. It fit a 160cm, average-build woman perfectly. Color: Trail Beige Size: XS [Excerpt from the official website] [sn] x YAMAHACK Collaboration T-shirt "A base layer you'll want to wear all the time, even in the mountains" A collaboration T-shirt with the mountain climbing web magazine "YAMA HACK," which delivers recommended mountain climbing equipment and information to people who love mountains, has been completed. We have shaped the "things that would be nice to have" for people who enjoy the mountains. It's called the "Mountain Basic Tee." This is a basic layer made from scratch, from the material and shape of the T-shirt. The material we were particularly particular about is a "merino wool x polyester blend" that balances the strengths of polyester and merino wool. It is an environmentally friendly material that uses recycled polyester. The fabric is 170 thick, making it slightly thicker and less see-through. The neck opening is balanced so that it is not too narrow and does not feel tight around the neck, making it difficult to see the innerwear. The short-sleeved type has a chest pocket as a single point. The seams are placed on the back, and a method called flat seaming is used to make the seams less irritating to the skin. The shoulder area is designed to be less irritating even when carrying a backpack. The hem is stylish with slits. Also, the back is made slightly longer to reduce the hem riding up when squatting. Material: 53% wool, 47% polyester (30% recycled polyester, 17% virgin polyester)