String Theory Colorworks' Inertia yarn is the perfect sock yarn. Made of 80% Superwash Merino, 20% Nylon, it's 400 yards (365 meters) of self-striping sock yarn. Plus each skein comes with a unique stitch marker that is color matched to the skein! The yarn band gives information of exactly how it will stripe. This is a must have for all you sock lovers out there!