watchOS 4.3.1 (build 15T567) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-05-29T17:08:30Z. The update package is 656.15 MB. This is a delta (partial) update that requires 3.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 7cfc126f1bf0ea5ecdbd29918303fc9132f748e5.zip.