set of scale, ruler with 10, 15, 20, 30 centimeter, 4, 6, 8, 12 inches with markup and numbers.

ruler 12 20 inch mm meter measure foot cm 30 15 set chart scale education centimeter graphic growth horizontal length long math number precision school tool unit accurate bar dimension distance gauge indicator quantity size gradation imperial metric yardstick calibration icon line millimeter tall silhouette tape sticker