watchOS 5.2.1 (build 16U5079d) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2019-03-28T17:11:23Z. The update package is 475.16 MB. This is a delta (partial) update that requires 5.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 18ab4bed8a08e6db72880d0bfb4983b1a95f2806.zip.