Made of Baltic Birch and smoothly finished for easy use with your handmade socks. The ruler features a suggested shoe size chart based on the ISO/ITS Footwear Sizing Guide. Use the ruler to make sure your finished socks will properly fit the recipient. This device also includes a needle gauge so you can confirm the diameter of any needles that are hard to identify. The ruler can also be used to check row gauge through the slit in the middle. A true multi-tool!