Arc Audio 8D4 8” 4 Ohm subwoofer Designed And Engineered In The USA High-Temperature Black Anodized Voice Coil Linear Design For Improved Dynamics And SPL At Low And High Volumes One-Piece Molded Rubber Surround Stamped Steel Basket Progressive Flat Layered Spider With Integrated Tinsel-Leads Designed For Small To Moderate Sized Sealed And Ported Enclosures Mounting Depth 5-3/4" Cutout Diameter 7-1/8" Minimum Sealed Enclosure - 0.35 cu ft Optimum Sealed Enclosure - 0.45 cu ft SPL Sealed Enclosure - 0.55 cu ft Specifications - Power Handing (Peak) - 300 Watts Power Handling (RMS) - 150 Watts Impedance - Dual 4 Ohm Minimum Sealed Enclosure - 0.35 cu ft Optimum Sealed Enclosure - 0.45 cu ft Maximum Sealed Enclosure - 0.55 cu ft Cutout Diameter - 7-1/8" Mounting Depth - 4-1/2"