watchOS 5.3 (build 16U5558b) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-06-24T17:25:31Z. The update package is 169.38 MB. This is a delta (partial) update that requires 5.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: ef8140e9a97e6c1c61e6b521bf38cd3bb01d8a8a.zip.