Backup files in The Observer are expected to have a .vpb extension. However, after making a backup file and saving it to the hard drive, the file extension may not show up in File Explorer.
This results because Windows by default hides extensions for known types of files. In order to see all extensions, even for known file types, make the following changes.
In File Explorer, tap the Alt key to see the menu, then under Tools pick Folder Options. Click the View tab and uncheck the option "hide extensions for known file types."
In File Explorer, select the View menu, then check the box for ‘File name extensions’: