These chunky pull on slipper bootie style socks are knit from a rustic natural yarn from the Shaker Society in New Gloucester Maine. This wool is coarse and sturdy and works well over a sock on a cold winter day.It was knit with a double strand so the socks are extra thick and warm. They have a collar type neck that is open in the back for ease of access. These do not have a non skid surface so they are best with carpeting or for sleeping. My kids love these things. They are sized for a mid age child, ages 6-12 ? They are 7.5 " along the footbed and stretch to 8.5" . As with all fine fibers, they should be hand washed and laid flat to dry . They will felt if machine washed. They are a dark midnight blue that looks almost black or steel gray in some lights.