watchOS 5.2.1 (build 16U6113) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2019-05-13T17:16:46Z. The update package is 129.89 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: 1c20699f5c034225dedca3c5e3b98810d5e8ffc5.zip.