Manufactured in the USA these Swatch/Needle Gauges are made of durable white plastic. It 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 stithces/rows fit inside the cutouts. The tool is double-sided for US/Metric and knitting/crochet differentiation.