Apple Inc. on Wednesday unveiled its first foldable phone, the iPhone Duo, featuring a 7.6-inch Retina display when unfolded and a 5.4-inch external screen. The iPhone Duo is equipped with a 48-megapixel main camera and an ultra-wide-angle camera, with a hinge made of 5-grade aluminum. Starting at $1,999 (256GB storage), pre-orders will begin on October 16, with official market availability on October 23.