This sturdy tool is both a needle sizer and a knitting gauge measurer.
Sometimes the markings on knitting needles can wear off over time and it's hard to tell what size needle you have. This handy needle sizer measures every needle size from from 2 - 12mm.
The tool also has markings so you can accurately measure a 4" / 10cm swatch. Line up the measurer against your stitches and count the number inbetween the marked red lines. This section is also magnified, making your stitches even easier to count!