After the release of build 14915 for fast ring insider members, Microsoft Windows Insider team is now testing build 14921. The latest Windows 10 build 14921 and mobile build 10.0.14921.1000 is now under internal testing. The current internal build is compiled on September 3, 2016.
Recently, Microsoft had released last Windows 10 Redstone 2 PC build 14915 and first R2 mobile build 10.0.14915 for fast ring insiders. The company also released cumulative Update KB3176938 build 14393.105 for Windows 10 Anniversary Update users. Microsoft also released Xbox One Preview update for members today.