iPadOS 9.1 (build 13B143) is an official Apple over-the-air update for the iPad 4 (GSM), released on 2015-10-21T17:15:53Z. The update package is 190.1 MB. This is a delta (partial) update that requires 9.0.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 3cb6e22ecb205f73ce6ca78cb4e5943b2fef9231.zip.