watchOS 5.0 (build 16R5283r) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2018-06-11T17:06:56Z. The update package is 562.62 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: f82e29bed2ec4c08a748119c099ec41568003ada.zip.