watchOS 5.3 (build 16U5526f) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-05-15T17:12:37Z. The update package is 140.81 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: ef532fdafe0e291ef970be99847e5ccbed931e06.zip.