watchOS 5.2.1 (build 16U5110a) is an official Apple over-the-air update for the Apple Watch Series 4 (44mm, LTE), released on 2019-04-29T17:40:00Z. The update package is 184.9 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: a95cbb3db256c372b212c0e86f18c32db2f17e72.zip.