Windows 10 Build 10147 is a pre-release build of the Microsoft Windows 10 operating system. This build leaked on 2015-06-18. On 2015-06-18, this build leaked onto the Internet. It contains many improvements over build 10130, the latest available public preview build at the time. The desktop UI (the look and feel of the controls, title bars, etcetera for desktop applications) has been updated to better suit the overall cohesion of the UX. This is the first Windows 10 build known to implement many hallmarks of RTM-style activation. When clean installing, you are prompted for a product key twice . It should also be noted that the key previously used to activate no longer works with this build. However, activation appears to carry over when updating.