watchOS 4.3 (build 15T5165e) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-01-25T18:04:08Z. The update package is 614.6 MB. This is a delta (partial) update that requires 3.2.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f151161e2f10fd4e297e37965e82665958f9ade7.zip.