watchOS 4.3 (build 15T212) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-03-29T17:09:37Z. The update package is 344.92 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: 80083927cc64950d125bedd7d7382f6a38fbe081.zip.