watchOS 4.2 (build 15S5102b) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2017-11-17T18:17:54Z. The update package is 89.16 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: 9379a01e89e3e096d8911e6602ce85dcb78dbdb4.zip.