watchOS 5.1.2 (build 16S5046a) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-11-15T18:09:08Z. The update package is 451.24 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: 3a7057e9a452a3cbc7b6d81a48a3f9ab859499f7.zip.