The Rolls HRD342 is intended for low cost, simple, time alignment of speakers in larger rooms or outdoors. The delay dial is shown in mili-seconds to make setup easy. The 32 to 360 ms shown on the dial will correlate to about the same in feet (32 ms = 32 ft). The Rolls HRD342 is inserted between the main console output and the amplifiers supplying the delayed speaker signal.