There are actually four file formats associated with the Momento software, but you will mainly deal with the MBK and MBF files. • MBK or Working file: the file you create and open in the software. It has a .MBK at the end of the filename i.e. Birthday.mbk • MBF or Master file: the file created when you click the Export button, and you send to Momento for printing i.e. Birthday MASTER.mbf • PDF or Preview file: a file created during the Export process, for you to proof your design before printing i.e. Birthday PREVIEW.pdf • BAK or Backup file: only required if there are issues with your MBK, please contact Momento if this is the case. Note: See more details in the Software Help.
To know exactly what kind of format your file is, be sure to use this tool https://www.filetypeadvisor.com/. It’s number one resource, when it becomes difficult to open the file due to an unknown format.