For precision measurement of metric items, INCRA's precision measuring tools will help you accomplish your project with accuracy. It is best used with a mechanical pencil for wood or scriber for metal. The 300 mm T-rule has INCRA's patented marking holes at every full, 1/4, 1/2 and 3/4 mm from 0 to 300 mm. It also has 0 to 50 mm height marking slots on the end in millimeters. Made in U.S.A.