watchOS 5.2.1 (build 16U5110a) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm), released on 2019-04-29T17:39:45Z. The update package is 136.25 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: 28854849c37e6bbec66fec971f3326e33d4f7cce.zip.