watchOS 4.2 (build 15S6102) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2017-12-05T18:01:58Z. The update package is 46.73 MB. This is a delta (partial) update that requires 4.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 87321474a3b9a4414e76f6853f92a3cd1c304c2e.zip.