iPadOS 8.1 (build 12B5410) is an official Apple over-the-air update for the iPad 4 (GSM), released on 2014-10-20T17:59:02Z. The update package is 1.8 GB. This is a delta (partial) update that requires 8.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5841fe6c5a387e84f5981cdeab134e6f67b8144f.zip.