Details

Measures the sizes of rings from A to Z, with all the half sizes in between AND tiny sizes smaller than A (5mm to 10mm) AND huge sizes larger than Z (up to Z 6).

ADVANTAGES:  heavy duty, the sizes are engraved into the metal, they will not wear off, this is the model recommended for regular use in a shop.

DISADVANTAGES: being 'engraved' you need good eyesight to read the sizes.  It only has UK sizes.  to see the alternative model.