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Apple iOS 4.3.1 for iOS devices been released. If you have upgraded iOS 4.3.1 and now wants to downgrade iOS 4.3.1 to 4.3, 4.2.1, 4.1 on your iPhone 4, iPhone 3GS, iPod touch 4G/3G, iPad 2/1G, then follow your step by step guide which makes you enable to downgrade from iOS 4.3.1 to 4.3, 4.2.1, 4.1. Before downgrading your must save SHSH blobs for the respective firmware.