Denon DN-F400 media player is a 1U/HE, half-rackspace unit designed for background music, message on hold, repetitive messaging, crisis management, or any application requiring audio to be running continuously or triggered at a moments notice. Denon DN-F400 features balanced/unbalanced outputs and is also controllable via RS-232C and GPIO (General Purpose Input/Output). DNF400 is perfect for amusement parks, retail outlets, police stations, public transportation, hospitals, hotels, restaurants, airports, museums, art galleries or anywhere a repeated audio announcement is needed.