watchOS 5.2.1 (build 16U113) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-05-13T17:17:58Z. The update package is 203.67 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: 12bd09627817beadeb894861d8aabcc6461fca72.zip.