Kent Double Sided Scale Ruler | Specially designed to facilitate the drafting and measuring of architectural drawings, such as floor plans and orthographic projections as the scale of such drawings are often smaller than life-size | Precision double sided scale ruler | Perfect for students and professionals | Easy to read calibrations | Scale - 1:1, 1:100, 1:20, 1:200, 1:25, 1:250, 1:50, 1:500