ALTO's black SXSUB18 18" Passive Subwoofer includes a frequency range and crossover designed to deliver smooth, low-end sound production from 35 to 200 Hz. Your kick drum will thud, your bass guitar will rumble, and your beats will inspire you to get your groove on when used with two- and three-way speaker systems. Because of its large low-end response, this passive speaker allows you to run your PA at a lesser volume while still getting a big, complete sound.