watchOS 5.1.2 (build 16S5046a) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2018-11-15T18:08:40Z. The update package is 734.56 MB. This is a delta (partial) update that requires 4.3.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: dab2f683995b123b35428e1027b8822ce11404b7.zip.