I am used to using BAK files to backup and restore my database on SQL Server... but my webhost is giving me backups of my online SQL Server database in a fileformat of .mbf

I can't find any info on how to restore a database from an mbf file. Books online doesn't even find any matches on a search for mbf, and google doesn't turn up anything either. How can I go about restoring my database with this file. Its a complete backup, not a partial (if it matters)