Android O’s Developer Preview 4 now available
The long-awaited official launch of the Android O update is finally close to reality as Google rolls out its fourth and final Developer preview for Nexus and Pixel Devices.
Developer Preview 4 includes the final system behaviors, new bug fixes and optimizations, and the final APIs (API level 26) already available since Developer Preview 3. Google has also released device system images of the Developer Preview 4, along with the stable version of the Android 26.0.0 Support Library.
You can simply get Developer Preview 4 by visiting this site and opt-in your device or you can download it here and flash it manually. The Developer Preview is only available in the following devices: Pixel, Pixel XL, Pixel C, Nexus 5X, Nexus 6P, Nexus Player, and the Android Emulator.
Source: Android Developers