watchOS 5.3.9 (build 16U693) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2020-11-05T18:19:29Z. The update package is 43.47 MB. This is a delta (partial) update that requires 5.3.5 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 8fb1766ffa279a17fd755a7c34e260b0d9c9d632.zip.