watchOS 5.1.2 (build 16S46) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2018-12-06T18:04:07Z. The update package is 683.21 MB. This is a delta (partial) update that requires 5.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 9ff783580478c8494eb8bd778c61307b449f55d3.zip.