watchOS 4.3 (build 15T5165e) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2018-01-25T18:03:56Z. The update package is 594.73 MB. This is a delta (partial) update that requires 3.2.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 67e2c1ea1f72da595183b1405da268d0e7263d1c.zip.