watchOS 4.2 (build 15S5102b) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2017-11-17T18:17:18Z. The update package is 189.72 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: cfc34c6ef5d4ad7f54f67584b5f0fe3b9f7ca1cd.zip.