Seachoice 6.5" (165 MM) Dual Cone Marine Full Range Speaker System 72109 Features: Resin Treated Cloth Surround Polypropylene Cone Dual Cone Design Specifications: Max Power: 180 W Nominal Impedance: 4 Frequency Response: 85 Hz-20 kHz, ±3 dB System Sensitivity (1 W/1 m): 86 dB Speaker Dimensions: A: Overall Diameter: 7.5"/ 191 mm B: Installation Hole Diameter: 5.47"/ 139 mm C: Mounting Depth: 2.24"/ 57 mm D: Grill Protrusion: 0.87"/ 22 mm E: Outer Motor Diameter: 2.76"/ 70 mm