watchOS 4.3.1 (build 15T5567a) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-05-14T17:13:52Z. The update package is 327.06 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: f7b6eed755dfe4ce648c700c1c908e4cd3cb3115.zip.