iPadOS 8.1.3 (build 12B466) is an official Apple over-the-air update for the iPad 4 (GSM), released on 2015-01-27T17:55:04Z. The update package is 137.41 MB. This is a delta (partial) update that requires 8.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 64c496dd01de9e02d720efe9b11bb8081b78710e.zip.