Duo System is an modern digital videointercom that Aci Farfisa offers all over the world. Duo System has been designed for a practical and fast videointercom installation, and the technology simplifies the medium/large size residential applications. Duo System operates on only 2 non-polarized wires allowing easy installation of even the most complex systems. Several entries and secondary door stations for each riser can be managed. The system is evolving as its technology progresses, therefore features, applications and performances increase following the new implementations. Many different external or internal stations can be selected for the best solution of the single installation. In particular amongst the available internal stations, users can find Echos monitor conceived only for color-version. With a strong identity thanks to the modern design in young and trendy style, Echos has hand-free conception. LCD 3,5-inch display, adjustable on horizontal axis for a better visualization of the picture, Echos has function-buttons for door-lock opening, auto switch-on and bell exclusion (with corresponding LED), audio volume and brightness adjustment. and completed with further 6 buttons for additional functions. Two colors versions are available: white with grey buttons and frame or "techno" metal grey colour. Echos works with both Farfisa door stations for Duo, which means profilo and matrix series will be available on the market.