watchOS 5.3 (build 16U569) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2019-07-22T17:27:56Z. The update package is 180.34 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: 4b8ed3a5bf3d4ccf350b3ef8d5ff2cc23e0a6c35.zip.