iPadOS 9.1 (build 13B143) is an official Apple over-the-air update for the iPad 4 (WiFi), released on 2015-10-21T17:15:52Z. The update package is 20.02 MB. This is a delta (partial) update that requires 9.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 613856bb0f6360f4ada0aedae7a3079b5ff0e028.zip.