.4b3 is STABCAL data
Key Features: .4B3 File Extension
What is an .4B3 file?
The 4b3 file extension is used for one of the files in the STABCAL - an older stability calculation for aqueous systems software. Seems like one of the supporting files.
This 4b3 file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.