Microsoft is also rolling out the first Redstone 5 preview build of HoloLens for Insiders who are registered in the Fast ring.

In order to install this preview, you must ensure that your HoloLens is enrolled in the Windows Insider Program and have the Windows 10 April 2018 Update for HoloLens installed. After installing the preview, check for updated preview builds with Windows Update.

Currently release notes have not been made available from Microsoft detailing what's new for HoloLens.

This article will be updated when release notes have been made available by Microsoft.