iPadOS 8.4.1 (build 12H321) is an official Apple over-the-air update for the iPad 4 (GSM), released on 2015-08-13T18:05:09Z. The update package is 40.43 MB. This is a delta (partial) update that requires 8.4 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: faa1ad62cb407fd6338ad39050bf01d6a587e7cb.zip.