A lovely little rainbow stack of connected discs for identifying knitting needle sizes US 0-15 / 2-10mm.
The discs swivel out and click back together with tiny magnets (which makes it as much fun to play with as use). 
 
Made from PLA, a 100% biodegradable, plant-based plastic substitute!
 
 
Product Details:
Each disc is imprinted in both US and mm needle sizes from US 0-15 / 2-10mm
Needle Gauge has 16 discs in total with a hole for the following metric sizes: 2mm, 2.25mm, 2.75mm, 3.25mm, 3.5mm, 3.75mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 8mm, 9mm and 10mm
Overall size (closed) is 2.5cm diameter X 4cm high (1" X 1.5")
Discs are in an array of rainbow colors
Gauge clicks into place with tiny magnets embedded on the underside of each disc
The discs are made from 100% fiber waste called polylactic acid, which is made from fermented plant starch such as corn, beets or sugar cane. It is 100% biodegradable and contains no plastic.
 
How to Use:
Swivel out the plastic disc to access the hole and insert your needle. The smallest hole that your needle fits into is your needle size. If the needle is unable to be inserted, select the next size up, or if there is excess space, try the next size down.