Unlike the modern "EaseUS Data Recovery Wizard" which is a 50+ MB installer that writes registry entries and temp files, version 5.6.1 Portable is a lightweight executable (often under 3 MB) designed to be run in-place.
The "Portable" aspect is the most critical feature of this software.
Many industrial machines, old POS (Point of Sale) systems, and embedded computers still run Windows XP or Windows 7. Modern recovery software often requires Windows 10 or 11, or at least .NET Framework 4.8. Version 5.6.1 runs happily on a Pentium III with 256MB of RAM.