Retro Calculator Snap-On iPhone 4 Case brings back memories of yester-year when life was much simpler - or much more complicated because you had to carry a calculator to school. Retro Calculator Snap-On Case is a form-ftting hard-shell cover with the looks of an old-school calculator on the back. The case not only looks cool, but protects your phone from bumps and scratches. Compatible with Apple iPhone 4 (AT&T, Verizon and all international/unlocked versions)