6.5-inch Coaxial Marine Speakers 30W RMS power handling 1/2-inch (13 mm) polymer dome tweeter Includes Sport Grilles.Specifications:General:- Continuous Power Handling (RMS): 30 W- Recommended Amplifier Power (RMS): 20 - 60 W / Ch.- System Efficiency: 87 dB 1 W / 1 m- System Nominal Impedance: 4 Ω- System Frequency Response: 55 Hz - 20 KHz ± 3 dBCoaxial Physical:- Frame Outer Diameter: 6.90 in / 175 mm- Bolt Hole Circle Diameter: 6.14 in / 156 mm- Frontal Grille Protrusion: 1.25 in / 32 mm- Mounting Hole Diameter: 5.00 - 5.25 in / 127 - 133 mm- Mounting Depth: 2.60 in / 66 mmIncludes Classic Grilles:- Salt & Sun Certified- 30W RMS power handling, perfect for source unit-powered systems- Bridge-mounted, 1/2-inch (13 mm) balanced-dome, polymer tweeter with neodymium magnet and ferrofluid cooling- Standard cutout size and mounting hole for easy retrofitting