watchOS 5.0 (build 16R5303d) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2018-06-19T17:36:28Z. The update package is 546.48 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: a15b1970cc47274d4630f8ed7b87ec14acc64cf1.zip.