watchOS 4.2.2 (build 15S5540a) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2018-01-09T18:13:04Z. The update package is 558.72 MB. This is a delta (partial) update that requires 3.2.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 86a19e136ce4c138c90df8f16fa24221b216cf90.zip.