3d model of the Imperial Code Disc greblie. It has appropriate dimensions:

• bottom disk is 1" (25.3 mm)
• middle disk is 3/4" (19.1 mm)
• the top disk is 1/2" (12.7 mm.)
• indentation in the center of the top disk about 1/4" (6.4 mm)

This is the version used by imperial officers, as belt/hat greblie.