watchOS 4.2 (build 15S102) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2017-12-05T18:00:45Z. The update package is 790.72 MB. This is a delta (partial) update that requires 2.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 64cf36cfcd4374fa870aaa60b6e3d397e661c43b.zip.