The Trekking family of sock yarns from Zitron have been in the hands of knitters for over a quarter century. The name XXL refers to the size of the skein (now 100 grams vs the former 50 gram offering). The line is constantly updated with solids, heathers, varigated, and self striping colorways.
Zitron is known as the "green yarn manufacturer" because each product in their line features all natural materials (with the exception of the nylon that is used for strength).
We have also mentioned before about the Oeko Tex 100 class 1 rating that their yarns have earned. The rating means that the yarn is safe for not only next to skin, but also in the mouths of babies.