watchOS 4.3 (build 15T5199f) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-03-06T18:08:08Z. The update package is 325.51 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: af55059e325bf606ebd8de0eaa26e26a2e64ba51.zip.