watchOS 5.3 (build 16U5569a) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm, LTE), released on 2019-07-16T17:15:06Z. The update package is 106.47 MB. This is a delta (partial) update that requires 5.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 72a28293d6bdb72dfc708dd56c3fce3f24d5a4b8.zip.