watchOS 5.3 (build 16U6569) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2019-07-22T17:29:15Z. The update package is 62.71 MB. This is a delta (partial) update that requires 5.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 53c8a462234149a11e36979282dbdb90c4323934.zip.