watchOS 4.3 (build 15T212) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-03-29T17:09:37Z. The update package is 369.81 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: 4554957476e906b40ee88332fda9e305a9219445.zip.