watchOS 5.2.1 (build 16U5110a) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-04-29T17:39:41Z. The update package is 166.35 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: f469eebb5a0654a26c42f9f5a6d34371fbf45c3f.zip.