watchOS 5.0 (build 16R5303d) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-06-19T17:36:40Z. The update package is 590.48 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: 53187480bca1254b7460285aea66f3943ce5390f.zip.