Microsoft has released the latest Windows 10 Insider Build to the Fast Ring. Windows Insiders are now downloading Preview Build 16299.15 on the branch. The significant thing about this version is that it very likely to be the release to manufacturing (RTM) build for the Fall Creators Update (FCU).

Since launching the Fall Creators Update for Windows 10 in May, Microsoft has been working on the platform through preview builds. Insiders has been testing new features over the months. In recent weeks the features have dried up as Microsoft focused on finalizing the FCU.

We already know that the Fall Creators Update will begin its official roll out on October 7. However, Microsoft has yet to say which preview build is the RTM versions. This is maybe a surprise because Windows Insider chief Dona Sarkar has usually been open about RTM builds.

Does this mean Preview Build 16299.15 is not the RTM? It is possible, but we are only two weeks out from the launch of the Fall Creators Update, so the RTM is certainly close.

There are some compelling details that make us think 16299.15 is indeed the RTM. For example, Windows Insiders on the Fast Ring now have the option to leave the program once the preview is installed.

Fall Creators Update RTM

Microsoft has not supplied this option on previous FCU previews. As we seen with the Windows 10 Creators Update, this option is made available when RTM is close.

It is also important to note that Microsoft says Windows 10 Preview Build 16299.15 will receive cumulative updates. Additionally, there is no build watermark on this release. All of these details are usually reserved for RTM builds.

Still, we will need official confirmation so will keep an eye on the Windows Blog and Sarkar’s Twitter account. I will update this article accordingly when Microsoft offers more details.