watchOS 4.2.2 (build 15S5530d) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2017-12-13T21:09:29Z. The update package is 178.87 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: 38ae99176e84adef71019df5eecc01f839d7c2fd.zip.