watchOS 4.3 (build 15T5187e) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-02-21T18:11:23Z. The update package is 340.24 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: da6ab8e1aff433fd96b7c9c68cf5151ba3f348d7.zip.