iOS 8.3 (build 12F5047f) is an official Apple over-the-air update for the iPhone 6, released on 2015-03-12T16:56:10Z. The update package is 124.5 MB. This is a delta (partial) update that requires 8.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 44584302dc1e9693f927c2a70053c26c48daf072.zip.