British Standard Plastic Ring Gauge Set of 26, Rings A-Z

Gauge will measure diameter and circumference in mm and inches.
Hollow cavity to store work tools like files, tweezers, gauges, etc.

Reverse side is metric carat measurement.

Capacity:
Diamond - 0.02 to 6 carats
Pearl - ½ to 40 grains

15mm Capacity; Graduations 1 to 10mm;
Throat 20mm.