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 925.22 MB. This is a delta (partial) update that requires 8.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c4f21ef515b11bb7b74c46f5be9873e6ae807137.zip.