Twig is a lineart iconset, icons specifically made for various sizes so as to retain the same line thickness. You will find these icons in the respective folders for 12px, 16px, 24px, 32px & 48px. Some of these folders contain less icons than others, use the 16px by default.
While working on some of their products, Wiredcraft wanted to have a simple, consistent and clean lineart icon set available in several sizes so that the thickness of the icons remained the same at various font sizes.
twig