watchOS 5.0 (build 16R5313d) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2018-07-03T17:11:12Z. The update package is 581.82 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: 173735721b3038efd951b5a875df4cb383b43603.zip.