watchOS 4.3.1 (build 15T567) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-05-29T17:08:31Z. The update package is 328.21 MB. This is a delta (partial) update that requires 4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b65de31f8e3567d607d3d4e2bf1724f0f343a882.zip.