Zanish Khan runs a tiny shop in Delhi's Basrurkar Market, where India's middle class comes to buy life's essentials. All around him, other merchants offer everything from electric fans to dried lentils that shoppers can scoop from 100-pound burlap bags. By contrast, Khan's merchandise is kept under glass and packed with state-of-the-art electronics. Still, Khan fits right in. India is in the midst of a smartphone buying binge, and Khan specializes in the oversized phone/tablet hybrids—or phablets—that enjoy great popularity in his country. His cases are stocked with models such as the Samsung Galaxy A5 and Grand 2, whose screens measure five inches diagonally. If that's not big enough, the Galaxy E7's screen stretches 5.5 inches.