watchOS 5.3 (build 16U569) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-07-22T19:19:52Z. The update package is 454.81 MB. This is a delta (partial) update that requires 5.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 4c4f542128b8b30703b1ec70a268a3d38377851b.zip.