
Apple has released iOS 9 Public Beta 2 for iPhone, iPad, and iPod touch users choosing to participate in the beta testing program for iOS. The new build arrives as 13A4305g, meaning it matches the 4th developer beta which was recently pushed out as well.
Eligible users can find the iOS 9 Public Beta 2 available to download now from the Over-the-Air Software Update mechanism within Settings > General > Software Update.
The download weighs in around 300MB for most iOS devices and installs quickly. Always back up an iOS device before installing any software updates, beta or otherwise.

Any iPhone or iPad user can choose to participate in the public beta testing program, though beta system software is notoriously buggy and less reliable when compared to a stable public release. Accordingly, it’s recommended to not run iOS 9 beta software on any primary usage device.
Participating Mac users will also find the second public beta of OS X El Capitan available through the Software Update mechanism on their computers.
iOS 9 will be released to the general public this fall, likely alongside the release of OS X El Capitan.