Amazon.com: PRV AUDIO Low Pass Crossover 1DF180B Low-Pass Filter for Speaker and Subwoofer Crossover Point at 180 Hz with Unique Selectable Features : Electronics
500 hz, 12db/oct High Powered Low Pass Filter (Crossover) for Subwoofer Enclosures | Reverb
Amazon.com: PRV AUDIO Low Pass Crossover 1DF180B Low-Pass Filter for Speaker and Subwoofer Crossover Point at 180 Hz with Unique Selectable Features : Electronics