كتلة ثقب مركزية دقيقة للحرف

This is something I've needed for a long time. Other tools which do much the same thing have been available, but are mostly horrendously expensive. This handy little item is very reasonably priced, perfect for my purposes and I'm sure it'll get used a lot.

There is a lack of writing in English or any instructions. QR codes seem to go nowhere helpful.
A diagram noting the size of the holes is needed.