watchOS 4.3 (build 15T5176c) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-02-07T18:10:05Z. The update package is 392.71 MB. This is a delta (partial) update that requires 4.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: de08dd5ec25db8f9e022f24ccb9588a9d65dcaf0.zip.