iPadOS 12.1.3 (build 16D5039a) is an official Apple over-the-air update for the iPad Air (WiFi), released on 2019-01-10T18:08:28Z. The update package is 31.62 MB. This is a delta (partial) update that requires 12.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 67c5063853719e5e8d5f55e859376b41892458fd.zip.