watchOS 5.2.1 (build 16U113) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2019-05-13T17:16:43Z. The update package is 174.91 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: e0e46df03b570467030c3ba499c624ce9143617b.zip.