watchOS 5.2.1 (build 16U113) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2019-05-13T17:16:50Z. The update package is 881.5 MB. This is a delta (partial) update that requires 4.2.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 69bbfd37730eddd6f942f2ec1cb67541e2353277.zip.