watchOS 5.1.2 (build 16S5046a) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-11-15T18:09:05Z. The update package is 570.59 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: 23c222c30d26a37aa673e0a9a58a6df76ae24ddb.zip.