Microsoft is now testing Windows 10 build 17620 internally. The new Windows 10 Redstone 5 build 17620 (10.0.17620.1000 rs_prerelease.180306-1449) was compiled on March 06, 2018.
Windows 10 Redstone 5 preview build 17618 is now available for Skip ahead Insiders. The new insider preview build brings back Sets feature for testers. This new feature is designed to make sure that everything related to your task: relevant webpages, research documents, necessary files, and applications, is connected and available to you in one click. In addition, there are various bug fixes and improvements.
The ISO files for Windows 10 build 17618 are also now available for download. You can download it from the link below.