watchOS 4.3 (build 15T5176c) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-02-07T18:09:24Z. The update package is 339.07 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: b5f0715d9d3ffd474405e39c5b625f5bd80fb4c7.zip.