watchOS 5.3 (build 16U5537b) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2019-05-28T17:12:12Z. The update package is 133.94 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: 7f445239f2d12fe2b21de7fb4fbbcf063636fcdf.zip.