watchOS 4.2 (build 15S5102b) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2017-11-17T18:17:39Z. The update package is 189.01 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: 998cbe6968f98132410ccd2808cf2d44a2f30cac.zip.