watchOS 4.3 (build 15T5187e) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-02-21T18:11:40Z. The update package is 374.06 MB. This is a delta (partial) update that requires 4.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a5093228e4628d1db5904437e5178aa905dfbc3d.zip.