watchOS 5.3 (build 16U569) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2019-07-22T19:16:09Z. The update package is 887.85 MB. This is a delta (partial) update that requires 4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f25a1e6753e4430db17a20d87da2e6d80d496b62.zip.