iOS 9.9.11.2.1 (build 15C153) is an official Apple over-the-air update for the iPhone 6s, released on 2017-12-13T18:13:27Z. The update package is 1.39 GB. This is a delta (partial) update that requires 9.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 6a6532c9ddc6d6ac874af09cbb14c98f5058835e.zip.