iPadOS 8.4 (build 12H143) is an official Apple over-the-air update for the iPad Air 2 (Cellular), released on 2015-06-30T15:51:17Z. The update package is 397.11 MB. This is a delta (partial) update that requires 8.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c54a828d9d956982ac3ac47c7e5462d94d3a857d.zip.