These are high detailed Imperial Code Discs made from 6061 aluminum. They are precision machined and are very accurate. Each greeblie is a set of three stepped discs. They have a 'V' shaped groove around the two largest sized discs. These greebles are found on Imperial belt buckles, hats, and helmets. I have a few options, both with or without the notch. The no notch greeblie is for the belt, and helmets and hats have a notch.
Available individually, as a set of 1 of each for a belt and hat combo, one no notch and two notches for a tie pilot, or the TIE pilot special pack with one no notch, two notches and the knurled cone with flat disc greeblie.
Most people fasten these with epoxy or e-6000 and some drill the hole out all the way through and affix with a pop rivet and riveting tool.