watchOS 5.1.2 (build 16S5042a) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2018-11-07T21:14:40Z. The update package is 734.45 MB. This is a delta (partial) update that requires 4.3.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 56e006d56d870fc4c524c5819258551fe6a5b905.zip.