Received the 2020 Good Design Award.
A ruler that is 30cm when opened and compact when folded. A compact ruler that can measure up to 30 cm when opened. When folded, it is not bulky in the pen case. There is a hole every 10mm, so it is convenient for marking.
It clicks every 15 degrees to measure the angle.
With a ground point scale that makes it easy to measure height and depth.