watchOS 5.1.3 (build 16S535) is an official Apple over-the-air update for the Apple Watch Series 2 (42mm), released on 2019-01-22T18:11:07Z. The update package is 138.68 MB. This is a delta (partial) update that requires 5.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5862353dcd224de839860ef3d3df7b73e20f7dee.zip.