Designed in New Zealand for accurate sizing of crochet hooks and knitting needles.
Brilliant little tool - made from clear acrylic.
includes a handy 5cm / 2 inch measurement piece. Laser cut and printed for precision and also to ensure the measurements won't rub off.
Measure the size of your crochet hook by checking the shaft diameter which is the part of the hook you work on the most. And a handy little chart for size conversions included.
Use instructions can be found here