watchOS 4.3 (build 15T212) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2018-03-29T17:08:45Z. The update package is 686.23 MB. This is a delta (partial) update that requires 3.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f0bbe9568e23522aa246840341ef4c51560cf6c0.zip.