watchOS 5.0 (build 16R364) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2018-09-12T19:18:28Z. The update package is 737.94 MB. This is a delta (partial) update that requires 4.2.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 893d726e79f8b37490c091e487d80d2badcd4261.zip.