watchOS 4.3 (build 15T5212a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-03-16T20:09:44Z. The update package is 369.6 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: b0851bb375aa0cea716966cde0a1eeab9e7c0a88.zip.