IPSW Portal

Choose aProduct→Choose aPlatform→Choose aVersion→ClickDownload

Download 4.3.1 (15T567) for Apple Watch Series 3 (42mm, LTE)

Version:	4.3.1
Build:	15T567
Signed:	No
Size:	0.36 GB
Release Date:	2018-05-29 17:09:37
Upload Date:	2018-05-18 17:05:51

Secure download directly from Apple's servers