watchOS 5.2.1 (build 16U113) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2019-05-13T17:17:10Z. The update package is 497.35 MB. This is a delta (partial) update that requires 5.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c1b12ae06e8b15147505044845ab69654036ceac.zip.