This is a convenient gauge that can be widely used for knitting, sewing, and other crafts. Approximately 13cm. - Knit Gauge: Accurately measures stitch counts. - Pleat/Tuck: Accurately measures the width of folds. - Buttonhole: Accurately measures the spacing of buttonholes. - Scallop: Convenient for drawing wavy lines. I received this from an acquaintance who used to run a craft store. It is new and unused, but the product description paper has some discoloration due to being stored in inventory for a while. Please consider this before purchasing.