Weatherproof Bass Blockers for 6x9 Inch Speakers Installer 3 Pack Installer Jobber 3 Pack Guaranteed +/- 10% Tolerance, Weatherproof Axial Leads, Non-Polar 10% Capacitor Blocks Sounds Below 300 Hz (133 mfd @ 4 ohm), Reduces the drive signal. 6" x 9" Speaker Size Recommended although can be used for any application. The speaker size is our recommendation please be sure you want to block sounds below 300 Hz