watchOS 5.1.2 (build 16S46) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-12-06T18:04:29Z. The update package is 781.13 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: a02736c530244e24d99f7864bddfbaf036f0273d.zip.