watchOS 4.3 (build 15T5176c) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-02-07T18:09:55Z. The update package is 392.67 MB. This is a delta (partial) update that requires 4.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c42dce025822481e2695a2031c85a9fde29e179c.zip.