Whether you wear Birkenstocks or prefer Jimmy Choos, a pair of long socks is on the must-have list. Size: adult small, medium, and large Yarn: 3 skeins of Morehouse Merino 2-ply Needles:  double-pointed #3 or #4 (use the larger size if you knit tight or American style) Our Knee Socks are shown here in variegated black and white with kelly trim.