These great socks were knit with Opal Rainforest, 75% superwash wool and 25% nylon. This was my first attempt with Opal, but it won't be the last! It's a soft yarn and feels good when knitted. I knited this yarn slightly tigher than they recommend; I like to knit fingering yarns at 8 st per inch; they recommend 7 st. Even so, the sock was soft and comfortable on the foot. This is a woman's size sock, but the 100g ball should easily make a pair of man size with no problem.