Microsoft OST to PST Converter is the best choice among users for converting OST files to PST format. It easily converts multiple OST files into PST and PDF, EML, EMLX, MBOX, MSG, etc. Moreover, it imports OST files into Gmail, Thunderbird, Yahoo, Office 365, etc. 

Read more: https://www.msoutlookhelp.com/ost-to-pst-converter.html