watchOS 4.2.2 (build 15S5540a) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-01-09T18:12:47Z. The update package is 65.78 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: 32991209623cad09868976772e9ef50843b68d52.zip.