This needle gauge is a multi-purpose tool used to help determine gauge and measure your needle/hook sizes. In addition, there are handy conversion charts and yarn standards tables for reference. Simply place the tool on your swatch and count how many stitches/rows fit inside the cut outs (along the bottom for stitch gauge and up the side for row gauge). The tool is double-sided for US/metric and knitting/crochet differentiation. Made in the USA. Measures approximately 5.5" (14cm) square.