watchOS 5.1.2 (build 16S5046a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-11-15T18:09:00Z. The update package is 168.1 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: bf74da5be7e09290a77457a2a5c30e532f8b0626.zip.