Microsoft has re-opened the Skip Ahead Ring for Windows 10 Insiders. There are a limited number of spots available for the skip ahead ring, so if you are at all interested in joining it, you should do so soon. Microsoft is getting ready to start distributing builds from the Redstone 6 branch of Windows 10 for the upcoming Redstone 5 builds. This allows you try out and test new features way in advance, but it should be noted that skip ahead releases tend to be the buggiest, so you should not join this ring from your main or production computer.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-opens-skip-ahead-ring-for-windows-10-redstone-6-insider-builds/