watchOS 5.1.2 (build 16S46) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2018-12-06T18:04:05Z. The update package is 752.69 MB. This is a delta (partial) update that requires 4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 402e3931e4959c5baad95d05aaed352f7a2a6fc4.zip.