watchOS 5.2.1 (build 16U5113a) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2019-05-07T17:19:07Z. The update package is 159.69 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: f818ccc30de621400556add34773224715631b2a.zip.