The iPhone 4 cases should work on the iPhone 4S as long as the iPhone 4S you're getting is from Verizon. If you're on AT&T, it won't work since the buttons on the side have been moved a few millimeters. (Volume up, volume down, and mute button)
For more info, visit this website:
https://icollectgadget.wordpress.com/2011/10/09/how-to-choose-cases-for-iphone-4s-and-iphone-4/


