Alvin 111PY engineer's scale ruler. 12" triangular drafting scales are ideal for scholastic and vocational use. Satin finish, high-impact plastic with tapered edges. Sharp, easy-to-read graduations resist wear. Eye-saver yellow. Graduated as follows: 10, 20, 30, 40, 50, 60 parts to the inch. Quality-made in Germany, perfect economical engineering scale for schools and colleges.