Apple is testing at least three iWatch designs based around flexible OLED displays, according to Korean publication The Chosun Ilbo. These include units with 1.3-, 1.4-, and 1.5-inch displays. The largest of those sizes would still be a tenth of an inch smaller than the Samsung Galaxy Gear.
Going with a flexible OLED panel would allow Apple to build a watch that conforms more closely to the shape of a person's wrist. The real challenge for Apple, however, is believed to be equipping the device with enough processing power while also giving it enough battery life to last a full day (or more) on a single charge. The company is also thought to be equipping the iWatch with a number of motion and health sensors, further cramping available space.