watchOS 5.1.3 (build 16S535) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2019-01-22T18:11:00Z. The update package is 750.46 MB. This is a delta (partial) update that requires 4.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 4b64dfaca1f6fe300bd3d8d652af96f92ae1c752.zip.