Niles HD6 Speakers 6-1/2" Injection-molded TCC (talc, Carbon, And Ceramic-filled) Polypropylene Cone Is Extremely Rigid To Reduce Breakup And Lower Distortion Butyl Rubber Cone Surround Damps Resonance And Provides Exceptional Durability High BL Magnet Structure With Vented Pole Piece Insures Powerful Bass Response Proprietary Tweeter-adjustment Mechanism Ratchets In 1mm Increments And Then Pivots For Precise Aiming Of High Frequencies 1" Tri-laminate Teteron Dome With Fluid-cooling And Ultra-wide Dispersion For Clear And Detailed High-frequencies