watchOS 4.3.1 (build 15T6567) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-05-29T17:08:38Z. The update package is 58.55 MB. This is a delta (partial) update that requires 4.3.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5fa086cce3048ee857487f9564122302ad77338c.zip.