watchOS 5.3 (build 16U5569a) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2019-07-16T17:14:21Z. The update package is 77.61 MB. This is a delta (partial) update that requires 5.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: fabe39b42a9558b5a552f069e10a96eac0161c77.zip.