watchOS 4.3.1 (build 15T5565a) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-05-07T17:23:11Z. The update package is 147.01 MB. This is a delta (partial) update that requires 4.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 2cef1aaf10e53de988ea3ae26c9e096203d488d1.zip.