This is a set of 6 cork rings. Outer diameter: 30mm, Inner diameter: 6mm, with low processing accuracy. They may appear to be low-grade, but this is simply because they haven't been filled with putty or bleached. Experienced users should have no problem using them. For filling holes after cutting, we recommend Justace cork putty. After applying the putty and sanding with 800-grit sandpaper, only the putty will be removed, leaving the cork untouched, resulting in a clean finish.