watchOS 5.3 (build 16U5569a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2019-07-16T17:14:24Z. The update package is 174.27 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: e40e4509e01a397f19ddfda14785e93632de21fc.zip.