watchOS 5.3 (build 16U569) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2019-07-22T17:28:04Z. The update package is 154.05 MB. This is a delta (partial) update that requires 5.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b8af219e4e28d1559e24aecaa13ea97d3fcf5298.zip.