watchOS 4.2 (build 15S5102) 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 46.77 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: 209effb455db95da85a495ac88d2da7328aabe8d.zip.