First-class architect, second-class architect, design and drawing exam. This is a drafting adjustable slope ruler. A versatile triangle ruler that easily measures angles, slopes, and gradients. - Type: Triangle ruler - Size: Approximately 25cm Thank you for viewing. This is a used item stored at home. Please consider purchasing if you understand. The knob is missing. I had it as a supplementary tool. I am also selling a complete one separately.