iPhone while everyone else was busy trying to keep up with iPhone, were busy creating amazing new features that make iPhone more powerful, easier to use, and more indispensable than ever. The result is iPhone 4. The biggest thing to happen to iPhone since iPhone. All the breakthrough technology in iPhone 4 is situated between two glossy panels of aluminosilicate glass - the same type of glass used in the windshields of helicopters and high-speed trains. Chemically strengthened to be 20 times stiffer and 30 times harder than plastic, the glass is ultradurable and more scratch resistant than ever. It's also recyclable.