watchOS 5.2.1 (build 16U5113a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2019-05-07T17:19:16Z. The update package is 143.86 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: 32c77c1a2d62ae161fad644034a854d4fa4cc08b.zip.