This aluminum multi ruler is a sleek, convenient, and portable tool! When fully extended, the ruler measures 30 cm (11.8 inches) long. However, when it's not in use it easily folds in half, thus becoming compact and easy to stow in a pencil case. The two halves snap right together when extended, making it easy to smoothly draw longer lines. The durable aluminum material also makes it perfect for use with a craft knife. Laser-engraved millimeter marks, plus 0.5 mm marks for the first 5 centimeters, are clear to read and won't fade over time. One side of the ruler has the "zero" measurement starting at the very edge of the ruler, so you can just hold the edge of the ruler to the edge of what you are measuring. This is convenient for measuring heights and depths, where an extra gap between the "zero" mark and the actual end of the ruler may get in the way. This multi-functional ruler also serves as a protractor—the central rotator has tick marks at every 15°.