The first 2-way slider Windows Mobile smartphone to hit the US, the Duo pays homage to its distant relative the Helio Ocean. The Duo is one of the smallest Windows Mobile 6 smartphones on the planet, if not the smallest. Though by no means thin, it's small in every other way and weighs only 3.9 ounces. AT&T offers the Duo which features HSDPA for the US, quad band GSM and support for CV streaming video, XM radio and MP3 playback. It's got a 1.3 megapixel camera, Bluetooth 1.2 and a 416MHz processor. With both QWERTY and number pad sliders, the Duo also has very good ergonomics.