80% superwash merino wool and 20% nylon ultraspun into a smooth, soft, dense, elastic yarn! This yarn is unbelievably soft and very smooth, giving wonderful stitch definition. It is 3 ply and dense so it wears extremely well. It also has a little very fine nylon blended into it to help it wear well, but it is difficult if not impossible to feel the nylon - not even remotely scratchy or stiff. You get the benefit of tough as nails hard-wearing socks after all your hard work AND the extra-plush ultrasmooth butter softness of beautiful merino yarn to knit (and wear). The yarn comes in a generous 4 ounce skein (not 100g!).