ChiaoGoo Two-Sided 5-Inch Swatch and 21-Hole Needle Gauge US 000 (1.5 mm) – US 15 (10 mm)

The ChiaoGoo-Needle Gauge measures 5-1/2 inches (14 cm) square. You can use this sturdy laser-cut plastic tool to measure your knitted gauge and the diameter of your knitting needles and crochet hooks. 

It includes conversion charts for metric vs US sizing vs UK/Canada sizing of knitting needles and crochet hooks. It also includes standard reference tables for yarn types and corresponding needle/hook sizes.

To check the gauge of your knitted or crocheted swatch, place the tool on your swatch and count how many stitches/rows fit inside the cut-outs. The bottom measures stitches per inch or centimeter and the side measures rows per inch or centimeter.