It all means that operating system is available for download on the Production, Slow, and Release Preview rings. Build 10586.164 is just another cumulative update to address a number of issues on the operating system, and it does not brings new features. In addition, if you have a handset that is currently running Windows 10 Mobile, but it’s not supported to receive Redstone previews, then you must switch to the device to the Slow or Release preview ring to get the new update. A: This release is being sent to Retail open market devices as well as our Insiders in the WIP Slow and Release Preview rings. Q: I’m in the WIP Fast ring.  How do I obtain this .164 release? A: Change rings in the Windows Insider app to either WIP Slow or Release Preview, take the update, and then change back to the WIP Fast ring. Q: My device already has a Redstone build on it (14xxx).  Does this build apply to me? A: No.  This is a cumulative update for devices on the Threshold 10586 build. Q: Why is it necessary for WIP Fast users to switch rings? A: It’s a publishing limitation.  Changing rings will not be a permanent process, but it is required for this particular release. Q: Why didn’t Insiders get to test this release before releasing it to Retail users? A: Insiders did get to test it!  The previously released 10586.122 build is nearly identical to this new .164 build.  There are no major feature changes between the two builds.  Changes were focused on a few key bug fixes and other required updates to ensure this build was ready to release to Win10 Retail devices. Alongside the update for Windows 10 Mobile, Microsoft is also releasing build 10586.164 for the PC version of Windows 10 that brings a number of improvements and security fixes for the operating system.  Source Twitter, Microsoft Answers via Neowin All content on this site is provided with no warranties, express or implied. Use any information at your own risk. Always backup of your device and files before making any changes. Privacy policy info.