FineSplit is a simple and tiny utility (just 5 KB), totally free and that runs under MSDOS environment, whose mission is to divide any file into smaller ones.
By default, FineSplit is configured to divide it according to the size of the diskettes, so that you can store and transport any type of file comfortably into smaller units.
If in FineSplit you want the partitions to be of a different size, then you must download the attached INI file from the author's website where they indicate the parameters to be used. In this way, you will have very large files partitioned into smaller ones just the size you want to make them more manageable.
You can free download FineSplit 32, 64 bit and safe install the latest trial or new full version for Windows 10 from the official site.