watchOS 4.2 (build 15S5102b) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2017-11-17T18:17:30Z. The update package is 145.3 MB. This is a delta (partial) update that requires 4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: ccd5cd7b2ba88230fbc0f7038965ef445d78ad4f.zip.