watchOS 5.0 (build 16R5360a) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2018-08-24T17:14:00Z. The update package is 605.46 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: 8a79269d8312187b13144989c825c372fb5a42a4.zip.