A few years ago first Klippel-optimized Radioactive-subwoofers were manufactured. Since then they have been one of the most popular subwoofers in the market due to their reliability and performance. Now it is time for a new generation that is even better! HighRoll sandwich surround is double stitched to reinforced paper cone. 2.5″ voice coils are wounded of copper wire and their cooling is very efficient. Oversized motor is mounted to rigid steel frame that keeps this package tight. These drivers work well in various types and sizes of enclosures. Once again Ground Zero sets new standards to midprice subwoofers.