iOS 9.2.1 (build 13D15) is an official Apple over-the-air update for the iPhone 5 (GSM), released on 2016-01-19T17:59:42Z. The update package is 966.83 MB. This is a delta (partial) update that requires 8.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 57f393538f049734b245138d3b127dff86d66e2b.zip.