watchOS 4.3 (build 15T5176c) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-02-07T18:09:26Z. The update package is 313.26 MB. This is a delta (partial) update that requires 4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 149517ba8fa86491fa4127e23aa86c4ec8c0066b.zip.