Apple has just released the iOS 9.0 Beta 4 build 13A4305g, for those registered with the Apple Developer Program.
The fourth Beta of the upcoming iOS 9 for Appliances iPhone, iPad, iPod and is available for download in IPSW images for selected devices directly from your Apps Developer Account Member Center
Users who are not enrolled in the Apple Developer Program will be able to update their devices in the coming days when Apple makes the information via OTA (Over the Air) updater.
However, be reminded before installing it public insurance beta you should know that it is a pre-release of the upcoming iOS 9 and is not designed for devices you use.
So if you care about its stability deviceς καλό θα είναι να αποφύγετε την installation.