watchOS 4.3 (build 15T5176c) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-02-07T18:10:25Z. The update package is 313.28 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: 57d255bd1ef20449c8c257ebcdd83edb4c1382cf.zip.