watchOS 4.2 (build 15S5100a) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2017-11-13T18:03:52Z. The update package is 189.83 MB. This is a delta (partial) update that requires 4.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f22d0d02eb24684cad31122607fb2b90234d8580.zip.