With this accessory from the Pimp-my-Zollstock series, you can use any standard folding ruler according to the principle of a spirit level. It's ideal for horizontally aligning workpieces or pictures. The bubble level is encased in high-quality, durable plastic. Simply slide it onto the ruler, and your leveling aid is ready for use. The bubble indicates the correct alignment. A clever helper for home, household, and hobbies that fits in any drawer.