watchOS 5.3.7 (build 16U674) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2020-05-18T17:31:44Z. The update package is 39.91 MB. This is a delta (partial) update that requires 5.3.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 543221a776ac0cf9818a758c5b037fd9f6b09727.zip.