Susan Bates Knit Chek is a handy tool to check your stitch and row gauge for both knitting and crochet. Not sure what size needle or hook you have? You can also verify the size of your needle or Susan Bates in line crochet hook from sizes U.S. 0-50 (2 mm to 25 mm). Knit-Chek measures only 5 x 3″ making it the perfect size for traveling or storing away with your other knitting or crochet necessities.