watchOS 5.3.7 (build 16U674) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2020-05-18T17:31:49Z. The update package is 64.93 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: ad9558a924a57076dc87cec9dc4c909b289a955d.zip.