watchOS 5.2.1 (build 16U6113) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm, LTE), released on 2019-05-13T17:18:11Z. The update package is 149.82 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: 96c904cac220574f875895847826ee3de865a2e3.zip.