One of the upgrades present with Apple's rumored iPhone 8 is a switch to stainless steel for the device's frame. While the highest-end iPhone, which is said to cost over $1,000, offers stainless steel, the regular iPhone 7s models are still reportedly going to use aluminum.
DigiTimes claims the 5.8-inch iPhone 8 has an OLED display, glass casing, and stainless steel frame. Those claims have been mentioned in the past.
A recent report from Mac Otakara said the 4.7-inch iPhone 7s and the 5.5-inch iPhone 7s Plus are both going to use the iPhone 7's aluminum design. Their primary changes will be internal, including a switch to the A11 chip.