There are no size restrictions on the files you wish to protect. Folder Protect doesn't only protect all types and formats of files, but it allows you to choose from which extensions or formats of files you want to protect in particular. So, if you're a businessman and want to protect doc, pdf and psd files or if you're an artist and want to protect your copyrighted mp3, mpg or flv files, you can protect those extensions and leave out all the rest. To use extension-wide protection, run Folder Protect and select how do you want to protect, then click 'Masks', select extension that you want to protect e.g. *.mp3, and click 'Add'. A small window will open that asks you to specify the path where you want this extension to be locked, provide the path and click 'OK'. Note: No drag and drop functionality available for masks in the program interface.