Precision and Accuracy: 30 cm ruler features 3 sides with 6 different scales. ^ You will calculate dimension and perspective for plans and other blueprints without struggling with the guesswork. ^ Material: Made from high grade anodized aluminum, reliable and skillfully crafted for your most project needs. ^ Laser Etched: Architect ruler for laser etched, They will not wipe or scratch off ever. ^ Widely Application: Good for technical artist, architect, engineer, plan drawer, hobbyist, modeler, graphic designer, student.