watchOS 5.3.4 (build 16U627) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2019-12-10T18:22:24Z. The update package is 56.89 MB. This is a delta (partial) update that requires 5.3.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 648856259d9c0728c06aa1a1c9e02f1be23a7166.zip.