watchOS 4.2.2 (build 15S5540a) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-01-09T18:13:27Z. The update package is 214.87 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: 5c05f3dbe20d5a7e1ebe97522e8f35897bfd17b4.zip.