watchOS 5.3 (build 16U5569a) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2019-07-16T17:14:18Z. The update package is 451.72 MB. This is a delta (partial) update that requires 5.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: df1f7e5f9b90c96e3bb4d7d7111315befa30178f.zip.