iPadOS 8.4 (build 12H143) is an official Apple over-the-air update for the iPad Air (China), released on 2015-06-30T15:51:13Z. The update package is 201.5 MB. This is a delta (partial) update that requires 8.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: bc61285c7ac074f6a94daf7733d06149029360b2.zip.