Transparent plastic triangle ruler set with precise scales. - Type: Triangle ruler set (40cm) - Material: Transparent plastic - Size: Set of large and small - Scales: Centimeter and degree markings Thank you for viewing. In drafting exams, commercially available 30cm rulers cannot draw lines in one go when drawing lines at the top and bottom of the drafting board, but this 40cm ruler can solve such problems. I also used this ruler to take the First-Class Architect drafting exam (I was not pointed out by the examiner, so it can be used at the exam venue).