watchOS 5.1.3 (build 16S6535) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2019-01-22T18:11:11Z. The update package is 65.01 MB. This is a delta (partial) update that requires 5.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 49787ba34b6288d4212b1b15a2a7c2371657b551.zip.