watchOS 5.1 (build 16R5568d) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2018-10-02T17:14:14Z. The update package is 735.4 MB. This is a delta (partial) update that requires 4.3.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8fcfc6f1eac127e29062926ac0628089dce61423.zip.