The PRIME R1-HD4-9813 is a 4-channel 160 Watt complete kit designed specifically for 1998 - 2013 Harley-Davidson® motorcycles. This "Closed loop" design is a precisely matched (using equalization and gain) amplifier and speaker system for optimized output and reliability. Includes pass-thru outputs for future expansion of audio system by sending signal down to another audio component.