watchOS 4.3.1 (build 15T6567) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-05-29T17:09:44Z. The update package is 166.36 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: d1633ac48be8b640b8e98efa02ab7c0dd0bbda8e.zip.