This needle gauge/ruler is made from alder wood. It has holes to size knitting needles from US 0 (2.00 mm) through US 13 (9.00 mm). Depending on the style of your crochet hooks, it can also be used to size hooks and has the corresponding letters marked at each hole.
The ruler goes up to 2 inches. The dimensions of the entire piece is 4 inches by 2.5 inches.