watchOS 5.2.1 (build 16U5079d) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2019-03-28T17:11:05Z. The update package is 129.78 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: 8b65d8407a53bb926324be304557c566bd073e64.zip.