watchOS 4.3 (build 15T5176c) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-02-07T18:09:27Z. The update package is 299.92 MB. This is a delta (partial) update that requires 4.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c474be1e7db9a5540149cb38f6aa55ac00813406.zip.