Windows 10 build 16299.15 is now in the Fast ring October 2, 2017 by admin Tweet Today, Microsoft released a cumulative update for Windows 10 for PCs build 16299, bringing the build number to 16299.15. It’s only available in the Fast ring, and is likely the RTM build for the FCU. Read more… Neowin Related Posts:Windows 11 build 22581.100 servicing update released…Latest Windows 11 Dev Channel Build 25252.1010…Yet another Windows 11 servicing build 22581.200…Windows 11 servicing build 22598.100 (KB5014100)…Windows 11 servicing build 22598.200 (KB5014105)…