watchOS 5.1.2 (build 16S46) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2018-12-06T18:04:16Z. The update package is 735.64 MB. This is a delta (partial) update that requires 4.3.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 1cda3366bb209e236ef2e601a7e24ccb1b637a8d.zip.