The ruler shows up to three full millimeters and a twelve
The edge of a ruler is shown and shows the measurements for millimeters, beginning with 1, 2, and 3.
A wooden ruler is marked with an mm, or millimeter, measurement at its very end.
a ruler that has the numbers 1 2 and 3 on it
A normal wooden rule upclose to show the 1 through 3 mm measurements.