watchOS 5.3 (build 16U569) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2019-07-22T17:27:42Z. The update package is 451.91 MB. This is a delta (partial) update that requires 5.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 02ca0ea10deb2d52da3b6eded49241fcac2a5f01.zip.