Rapidesign Rapid-Reader II Ruler is unique ruler featuring center slot opening for reading computer printouts. Slot is ideal for making notations and highlighting. 1/6" and 1/12" scales measure lines per page vertically and 1/10" scale measures number of characters per line horizontally. 1/16" and cm scales included. Made in USA. Rapidesign has the world's largest selection of drafting templates for architects, builders, engineers and graphic designers.