iOS 9.2.1 (build 13D15) is an official Apple over-the-air update for the iPhone 6, released on 2016-01-19T18:20:41Z. The update package is 1.12 GB. This is a delta (partial) update that requires 8.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c18b3d6b7ccb7e4480fb3ebe73cac700099f4384.zip.