watchOS 4.3 (build 15T212) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-03-29T17:07:24Z. The update package is 647.52 MB. This is a delta (partial) update that requires 3.2.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a78be250aee3dd710b80b557c60c4bf269907920.zip.