watchOS 5.3 (build 16U6569) is an official Apple over-the-air update for the Apple Watch Series 4 (40mm), released on 2019-07-22T19:19:45Z. The update package is 111.58 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: 7503888a95e99c5080335168cd51ebe50fa5b292.zip.