IPSW Portal

Choose aProduct→Choose aPlatform→Choose aVersion→ClickDownload

Download 4.3.1 (15T5545b) for Apple Watch (38mm)

Version:	4.3.1
Build:	15T5545b
Signed:	No
Size:	1.08 GB
Release Date:	2018-04-16 17:03:45
Upload Date:	2018-04-12 17:16:51

Secure download directly from Apple's servers