watchOS 5.2.1 (build 16U5079d) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-03-28T17:11:36Z. The update package is 460.29 MB. This is a delta (partial) update that requires 5.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f9cf58c5e6696cce076aaae2b5bd89c450579bc1.zip.