watchOS 5.0 (build 16R5349a) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-08-13T17:06:58Z. The update package is 297.05 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: 9664cfadd9cc4fce0c93daf24bbb44972631402e.zip.