watchOS 5.2.1 (build 16U5110a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2019-04-29T17:38:47Z. The update package is 164.89 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: 79992e0fbd3c22aa0c0d1de0023dcea247dc74ab.zip.