iOS 8.4.1 (build 12H5321) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2015-08-13T18:05:03Z. The update package is 1.34 GB. This is a delta (partial) update that requires 8.4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: fc892038acfbf34374237041cfe79c7a8e50c32e.zip.