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 964.27 MB. This is a delta (partial) update that requires 8.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8531b7aeb0a144451e8e02d84b9ec8524506ec7a.zip.