watchOS 4.2 (build 15S5090c) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2017-11-06T18:03:28Z. The update package is 294.4 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: 652818043b3dd760f4e7a7b24d28017cf0054be7.zip.