Weatherproof Bass Blockers for 5x7 6x8 4x6 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. 5x7 6x8 4x6 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