watchOS 5.3 (build 16U5537b) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-05-28T17:13:04Z. The update package is 96.67 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: 1f6a77ab2679b919b4c203a7010326a0021cf68d.zip.