For the dual flashlights design and I'm wondering if all iPhone 5 case works on iPhone 5S?
No, iPhone 5 case is not compatible with the iPhone 5S.The answer is yes!
I think a better guarantee would be all 5s cases will work for the 5. Some 5 cases will work if they have a large cutout for the camera to begin with. Obviously, the bumper cases will work like Element.