watchOS 5.0 (build 16R5357a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-08-20T17:09:02Z. The update package is 653.68 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: 80f2d9d9e7a16a03e1ef89f97b9a9b5c907bbdee.zip.