watchOS 4.3 (build 15T212) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-03-29T17:08:14Z. The update package is 325.06 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: 66c03122b641e21f1123de0806f72fc9f16135f4.zip.