iOS 9.0.1 (build 13A404) is an official Apple over-the-air update for the iPhone 4s, released on 2015-09-23T17:55:21Z. The update package is 851.05 MB. This is a delta (partial) update that requires 8.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f913c5f08477eb6cdeb8cb4dbabf833c73692770.zip.