There are no leaks or other functional issues, it's just ugly AF.

I like the handles, but the missing flange drives me crazy and so the missing buttons. I have found some flanges and buttons online but the major issue that I have is that the flanges/replacements come in different sizes. For instance:

• 11-B size
• 12-H size

How do I measure what I have to figure out what I need?

Thanks in advance.