watchOS 5.3.9 (build 16U693) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2021-01-26T18:26:52Z. The update package is 492.44 MB. This is a delta (partial) update that requires 5.0 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 6d1151ec623e2c08bc8a2d1650653c60c0d54bef.zip.