Alongside the second build of iOS 9.2.1, Apple has also released iOS 9.2.1 Public Beta 2 to public testers. Similar to previous beta builds, iOS 9.2.1 Beta 2 is expected to be a minor update featuring bug fixes, under-the-hood improvements, as well as performance enhancements.
iOS 9.2.1 Beta 2 is now available through Software Update or via iOS Dev Center for registered developers, while public beta testers will get it via Software Update or through Apple's Beta Software Program.