PAC BB-2PR Pair of Bass Blocker Designed for 6" Speakers Removes selected frequencies from the audio source Protects the speakers from receiving damaging frequencies Designed for use with 6" and 6-1/2" speakers Pair of bass blockers Removes selected frequencies from the audio source Frequencies blocked: 4 ohms: 0-600 Hz / 8 ohms: 0-300 Hz Protects the speakers from receiving damaging frequencies Designed for use with 6" and 6-1/2" speakers