watchOS 4.3 (build 15T5165e) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-01-25T18:04:11Z. The update package is 314.41 MB. This is a delta (partial) update that requires 4.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 20509494e5b6001a05a81b08ddef2f6a76431ad6.zip.