watchOS 4.3 (build 15T212) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-03-29T17:07:20Z. The update package is 815.96 MB. This is a delta (partial) update that requires 2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b478b8358ca7d1969a4f64d518f341f89e076c0b.zip.