Quantum  Alpha Series QACW15D4 15-Inch 4 Ohms DVC Subwoofer 2.5-Inch 4 Layer DVC with Aluminum Former VAC PP Cone with Single Stitch Rubber Surround VAC Aluminum Dome Stamped Steel Frame EVA Gasket 15 inch 4 Ohms die cast subwoofer 2.5 4 layer DVC with aluminum former Non transfer paper cone with single stitch NBR rubber surround, Vac PP dome dust cap 140 oz Y30 magnet, Black Electro-plated finish top,bottom and yoke Mixed P/C spider, spring terminals