watchOS 5.3 (build 16U6569) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm, LTE), released on 2019-07-22T19:20:33Z. The update package is 160.35 MB. This is a delta (partial) update that requires 5.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: d7153d73f33bb3303feb5f35dd20e7b917612fff.zip.