Buffered MxFFS Archive - Internal Ring Buffer

Good day,
We are using Buffered MxFFS Archive as Primary and SMB/CIFS File Server chosen for Secondary.
When looking at Camera Status, the internal ring buffer is showing Maximum 192MBytes.

My question: Is this a reflection of the SD Card? There is no reference to the SD Card size within Camera Status page, is this correct?

Also, There was a post that mentioned, the MxFFS Archive size should be in increments of 4. Why is this? Does that comment assume the SD card is 4GB?

Thank you Kindly,