Teko Socks remains committed to merino wool as a core yarn within all of their socks. Teko"s process of combing merino with ultra fine recycled synthetic yarns has resulted in significant performance benefits including improved durability, faster drying times and overall improvements in both the comfort and fit of their Planet Positive socks. The Wikipedia definition of Synergy is "two or more things functioning together to produce a result not independently obtainable." Teko has dubbed their combination of merino wool and recycled synthetics: SIN3RGI. If you have not tried the Teko SIN3RGI socks yet, you (and your feet) are missing out.