iOS 9.9.10.2.1 (build 14D27) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2017-01-23T18:08:12Z. The update package is 1.32 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: 747fc9a8b0094e3967f6ed38ed71f7796ee06bf6.zip.