watchOS 5.1 (build 16R5589c) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-10-22T17:19:34Z. The update package is 747.99 MB. This is a delta (partial) update that requires 4.3.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b80419eeff76b913c2742926e031344db4447c75.zip.