need info on solo saddlebag

[kc5tf]

what is the value on a solo bag that replaces the rear seat and attaches to the rear fender

[Gryphon Rider]

I don't think we quite understand what you're asking.  To answer the question as best I understand it, the value (benefit) is that you can conveniently carry things with you on the bike.  But that is too obvious, so you must be wanting to know something else.  If you are shopping for such a bag, the thing you are looking for is called a tail bag, and they can be had for between $30 and $400.

Here's an example of the selection:
https://www.revzilla.com/motorcycle-tail-bags