watchOS 4.3.1 (build 15T567) is an official Apple over-the-air update for the Apple Watch (38mm), released on 2018-05-29T17:08:21Z. The update package is 97.57 MB. This is a delta (partial) update that requires 4.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5790296b418c608f7296e0c46a2a7254e078f1f9.zip.