watchOS 4.3 (build 15T5176c) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-02-07T18:10:18Z. The update package is 346.28 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: 6966385ff3eacdc3fd5a4a96f0c41aa7408327df.zip.