RE Audio SRX15D4 15-Inch Dual 4 Ohm Performance Woofer Kraft Pulp Cone, Rubber Surround Pressed Steel Basket, 4-layer Copper Voice Coil FEA Optimized Motor Structure, Double-stack Magnets Linear Spiders, Foam Gasket Normal Impedance: Dual 4 Ohm, Power Handling: 300W (RMS)