watchOS 4.3 (build 15T5187e) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-02-21T18:11:31Z. The update package is 317.63 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: d0abc375a3fc13a05b5fae852fc8d78378a0ad04.zip.