watchOS 5.2.1 (build 16U113) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-05-13T17:17:57Z. The update package is 453.13 MB. This is a delta (partial) update that requires 5.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8206751d3e42c9c34984584eaded426ed9c126db.zip.