HTC's Touch Dual features HTC's TouchFLO technology, aimed at simplifying the interface and allowing finger-tip, gesture-based access to the most used features of the phone. This runs on top of the Windows Mobile® operating system. As well as TouchFLO, gesture-based technology is seen in HTC's photo album software, using it to mimic some of the multi-touch and accelerometer-based features of the iPhone and other such devices.The addition of a sliding keypad is one of the main features of the Touch Dual, and this comes in two variants depending on model and geographic location. The 16-key variant is a standard mobile phone keypad, with four added buttons for the Windows Mobile® OS (Start, Internet Explorer, Messaging & Back). Meanwhile the 20-key variant is a QWERTY keyboard featuring the BlackBerry-style SureType layout, which does not feature the added Windows Mobile® keys. Both of the keyboards can appear virtually on the touchscreen, irrespective of model.