watchOS 5.1.2 (build 16S5046a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-11-15T18:08:56Z. The update package is 451.12 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: 013410f3694763172c555f0216c54574fa7ac24a.zip.