watchOS 5.3 (build 16U5569a) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2019-07-16T17:14:16Z. The update package is 111.27 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: 7ab2a979d77a35a70f070bda2cd5c9724f858c70.zip.