The digital technology of the beltpack offered new opportunities for the user interface. Inspired by the iPods of the day the volume controls wouldn’t need physical knobs (encoders) but could be engineered with capacitive sensors instead. For a beltpack, used in often poorly illuminated, difficult conditions ease of use is even more critical. The two large cavities in the front can be handled blindly. The overall design could therefore be carried out extremely smooth and follows the design philosophy of the desktop products with maximized simplicity and readability at the top. (see also Pro Line & Flexus)