watchOS 4.3 (build 15T5199f) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-03-06T18:08:09Z. The update package is 136.19 MB. This is a delta (partial) update that requires 4.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 9e7d0817f1a23d263c6ef1f3d10e232b6e7dddf9.zip.