watchOS 5.1 (build 16R5584a) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-10-15T17:09:55Z. The update package is 175.83 MB. This is a delta (partial) update that requires 5.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 855007b45e61e283de7fd865ae52ec1827a11e37.zip.