watchOS 5.3 (build 16U569) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2019-07-22T17:22:48Z. The update package is 983.59 MB. This is a delta (partial) update that requires 3.2.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 50a4ed0697465b848597d537a4dbbd97cb442f9a.zip.