watchOS 5.1 (build 16R5559d) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-09-18T17:22:36Z. The update package is 370.54 MB. This is a delta (partial) update that requires 5.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c7d720daf20b6376a091708b5d92eadd8b49b8f0.zip.