The 24" Fairgate # 12-124 Vary Form Curve rule is especially helpfull to the patter makers when drawing more defined curves of neckline and collar design, sleeve caps, pocket contour, armhole, and more. good for the patternmaker , graphic artist , illustrators or anyone who needs to draw or cut smooth curved lines. reading inch on both side Vary Form Curve Rule 24 inch Compatible for Fairgate ruler #fg12-124