watchOS 5.3.8 (build 16U680) is an official Apple over-the-air update for the Apple Watch Series 4 (40mm, LTE), released on 2020-07-15T17:28:38Z. The update package is 1.37 GB. This is a full OTA update that can be applied from any compatible base version. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 19c462faf582d35bace46ed4eb82e2239e3084cf.zip.