The 121NPM is a ultra high efficiency, (101dB 1watt / 1 meter) 12-inch mid bass woofer with incredibly linear frequency response characteristics, extreme high power handling capability while generating low harmonic distortion artifacts.-The 121NPM uses a lightweight carbon fiber loaded cone assembly along witha precision double roll constant geometry surround. This combination provides remarkable strength, high efficiency and aexcursion linearity of 7.5mm.Magnetic CircuitREDCATT engineers have developed a lightweight, neodymium outside ring based magnetic circuit capable of delivering the highest level of performance providing a consistent, high integrity magnetic flux gap,ultra low distortion characteristic and high efficiency cooling system. The magneticcircuit design is optimized to generate the minimum amount of flux modulation,providing exceptional stability.