SOLD AS A PAIR, Many Frequencies AvailableContact us if you need help selecting the proper frequency. The Harrison Labs FMOD is an inline active crossover simulator. FMOD's are passive so noise free and better than a much more expensive electronic crossover that requires power to operate. Frequencies available for every need such as Subsonic filter, Subwoofer, Woofer, Midbass, Midrange, Tweeter, Super Tweeter, Horns and Ultrasonic filter Combine with other FMODs and traditional electronic crossovers for bandpass ranges or to change the slope and crossover frequency point Install in seconds by placing the FMOD inline with the RCA patch cable running between the source (head unit.preamp.etc) and the amplifier Low Pass available Frequencies 50, 70, 100, 150, 200, 500, 1000, 2500, 3500, 6500, 20K High Pass Available Frequencies 20, 30, 50, 70, 100, 150, 200, 300, 500, 1000, 2500, 3500, 6500