This handy crochet hook gauge by Prym will assist you in verifying the size of your crochet hooks! Particularly useful for figuring out the sizes of those old hooks where the number has rubbed off. Each gauge has 13 measuring slots for sizes 2.00-10.00mm in both metric and US systems.
 
Measuring only 93 x 76mm, the Prym crochet hook gauge is sure to fit right in your craft tool bag or box.