Microsoft recently tested Windows 10 build 16266 for PCs. The new Redstone 4 build 16266.1000 (rs_prerelease.170810-1651) was compiled on August 10, 2017. In addition, the company also compiled mobile build 10.0.15243.0 on August 12.
The Windows Insider team is expected to release next insider build on August 17.
Previously, Microsoft released the Fall Creators Update build 16257.0 and Windows 10 Redstone 4 build 16257.1000 to Fast Ring insiders. The builds were released with new features, bug fixes, and improvements.
Now you can download Windows 10 build 16257 ISO from the link below.