watchOS 5.3 (build 16U5569a) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm, LTE), released on 2019-07-16T17:15:05Z. The update package is 115.49 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: 259ca4cf1d5eb9f8af9c1b655c158951f955e50f.zip.