Earlier today, Microsoft released Windows 10 Mobile build 10572 to Windows Insiders to Windows Insiders on Fast Ring. The latest build brings lots of new features and improvements.
Now Microsoft is rolling out Fast configuration update to Windows Insiders on Windows 10 Mobile Build 10575.
You will receive this update if you are enrolled to “Insider Fast” or commonly known as Fast Ring in your Windows Insider app. However this update doesn’t contain any changes or fixes as Gabe Aul already explained that this update helps Microsoft to target your device in correct ring.