watchOS 4.3 (build 15T212) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-03-29T17:09:31Z. The update package is 362.59 MB. This is a delta (partial) update that requires 4.2.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: fd3486744a611b1586c5db2ef34859add7602db7.zip.