watchOS 5.1.2 (build 16S46) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2018-12-06T18:04:13Z. The update package is 975.98 MB. This is a delta (partial) update that requires 3.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 2c428290d99344468f0e9789bbc3cbc98f219f63.zip.