watchOS 5.3.9 (build 16U693) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2020-11-05T18:19:32Z. The update package is 43.51 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: e6520cadefad6c0b4c8ecc414c19a1dd8391bff7.zip.