iOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPhone SE, released on 2017-12-13T18:14:20Z. The update package is 316.17 MB. This is a delta (partial) update that requires 11.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: d3e3d511cc769288d06bbc650e61b6c8dc3931f3.zip.