watchOS 4.3.1 (build 15T5565a) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-05-07T17:23:06Z. The update package is 326.95 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: cdd099a60970b38d33e18f8b59275421724415f4.zip.