watchOS 4.3 (build 15T5212a) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-03-16T20:09:01Z. The update package is 306.53 MB. This is a delta (partial) update that requires 4.2.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 116dfb3fc0723ee3945ed4e68588f80cefcb5208.zip.