ScanSpeak Revelator 18W8531G00 Audiophile 7 inch Mid Woofer 8 ohm This is a fantastic sounding speaker featuring ScanSpeaks outstanding quality and excellent sound - used in many top-of-the-line name brand audiophile speakers. Made in Denmark Works extremely well in both sealed and vented bass-reflex enclosures - F3 of about 55Hz sealed and can get down to 33Hz vented. 7 Revelator mid/woofer features a non-resonant cone and dust cap structure, dynamic linear suspension, SD-1 magnet system, Grasshopper cast chassis with maximized air flow and resonance terminating mounting system. Less resonance in all structures, lower compression and higher linearity, faster termination of excess energy and higher sound pressure capability.