1. The package includes: You will receive a total of 4 parallel ruler drawings, containing 2 specifications (15 cm / 30 cm), 2 of each specification, to meet your different needs. Independent and exquisite packaging makes storage more convenient for you. 2. quality materials: This rolling parallel ruler is made of plastic, featuring clear scales for easy observation, accuracy, smooth rolling, wear resistance, and corrosion resistance. It is not easily deformed or broken, ensuring longterm use. 3. Onesided double scale: Our multipurpose rolling rulers are marked with both metric and inch scales on the same side, allowing quick unit conversion without flipping the ruler. The builtin scroll wheel includes various formulas and conversion factors for convenient reference, enabling faster and more efficient drawing. 4. Easy to use: This parallel rolling ruler is made of transparent material, ensuring important numbers or texts remain visible while drawing. Each inch of the scale has a hole for marking or drawing circles, making it very convenient to use.