watchOS 5.3 (build 16U5526f) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-05-15T17:12:48Z. The update package is 74.52 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: 65d814c8cab90f68457a63f8777b1c7fc323073c.zip.