watchOS 4.2 (build 15S5090c) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2017-11-06T18:03:40Z. The update package is 216.26 MB. This is a delta (partial) update that requires 4.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 9d0a5f39b5934cf7b52536b8bcb232d42e09ce1f.zip.