watchOS 4.3 (build 15T5187e) is an official Apple over-the-air update for the Apple Watch Series 2 (38mm), released on 2018-02-21T18:11:39Z. The update package is 335.72 MB. This is a delta (partial) update that requires 4.2.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8d9201e811b04d26224cf9643bfb0e8c5282a293.zip.