watchOS 5.1.2 (build 16S46) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm, LTE), released on 2018-12-06T18:04:58Z. The update package is 202.24 MB. This is a delta (partial) update that requires 5.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 65eac04745fc7c5ae4dd79ad7f88ac93f5ab4f16.zip.