watchOS 5.3 (build 16U5569a) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-07-16T17:14:53Z. The update package is 199.15 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: 7efc61de0c46515bbf309bb793ec8d415863deb0.zip.