The Hoplite 2 is made of 100% merino wool (150gsm). The best sweat-wicking and breathable fiber known to man. This bottom is the most versatile base layer on the market. Whether used as insulation or as a stand alone item, the Hoplite II crew will keep you comfortable, warm, and prepared.
"Amazing hot waether layer, runs a bit short in arms and torso."
This is SUPER light weight, very thin. Tough (only has two small snags on the right arm after 2 seasons). The neck hole is quite wide, which can be a good (cooler) and bad(sunburn). Does run very short in the sleeves and torso. I wear a L in everything else and it fits perfect, but this is too short. I recommend you size up.