Diamond Linux-TT is a desktop Linux distribution based on the Stable version of Debian.
Stable version of Debian means security and no problems with updates.
The distribution uses the KDE Plasma desktop to make the operating system interface look very familiar to former Windows users.
Thus, Diamond Linux-TT distribution means:
• Linux operating system type Windows
• Operating system in 15 minutes
• Linux that does not require special knowledge or skills
• Free operating system for home and office use
Installation instructions
https://www.linux-tt.com/help/
You can download the ISO from here