Like the well-known Ocean that Pantech designed with Helio, the Duo (also known as the C810) is a dual-slider handset that sports both a traditional numeric keypad and a full QWERTY keyboard. In order to accomplish this, a few compromises had to be made. For one, at 102mm x 50mm x 22mm (4.0" x 2.0" x .9"), the Duo is not a particularly thin handset. Its 128g (4.5oz) weight isn't going to set any records either. But all in all, Pantech did a fairly good job of keeping the size and weight of the device under control, which keeps the Duo looking, for the most part, like any other slider smartphone.
The most interesting part of the Duo's physical design, as well as the part that involved the most compromises, is the slide out QWERTY keyboard. In order to keep the Duo's overall thickness in check, Pantech had to make sure that the QWERTY keyboard was very thin. This led them to use fairly soft rubber keys that don't provide very consistent tactile response. The space bar is particularly bad in this regard: pressing on the left or right edge of the key feels fine, but the key becomes very stiff feeling if it is pressed dead center. This lack of consistency, which is present on most of the keys (to a lesser extent), makes it hard for users to quickly and confidently enter text on the keyboard. One nice point about the keyboard is that numbers and symbols can be entered with a simple long press, removing the typically required Fn key shift from the input equation. The last keyboard related issue is the lack of a spring in the keyboard's slider mechanism. There is no snap open or snap close, which lowers the overall sense of quality the Duo otherwise exhibits.
The numeric keypad suffers no such problems. It is as good as, or better, than the keypad found on most other slider handsets on the market. The keys have a good feel to them, and the slider mechanism is spring loaded so that it confidently snaps closed and open. It is so good, in fact, that it just highlights the QWERTY keyboard's lacking in this regard. The rest of the Duo's controls are located directly below the main 262k color, QVGA (240x320 pixel) display, which is clear and bright, but prone to internal dust accumulation, as seen in our screen shots. The d-pad is a bit small, but works adequately well. The left and right softkeys, the home and back buttons and the red and green call keys also perform well. Under the d-pad sits a button marked with camera flash and lock symbols. This button, in spite of the iconography, brings up the Windows Mobile Quick List, which provides quick access to the wireless manager, the profiles, and a power-off option.