.CALIBRE File Extension
What is a CALIBRE file?
Data file generated by Calibre eBook management software; written by the Calibre software onto an attached eReader device (e.g., Kindle, NOOK) when it is connected to the computer; contains information that helps Calibre manage eBook information on the device.
Common CALIBRE files include driveinfo.calibre and metadata.calibre. If you delete these files, Calibre will recreate them the next time the device is synchronized.