Ground Zero GZIW 10XSPL-D2 subwoofer 10" (250 mm).

Ground Zero GZIW 10XSPL-D2 subwoofer 10" (250 mm).

High power 10″ SPL-subwoofer Klippel optimized Reinforced paper cone with 3D honeycomb structure 2.5″ copper voice coil High-roll sandwich surround Progressive 2-layer spider Push terminals Don´t get fooled by the affordable price! 
These budget class XSPL-monsters are designed with Klippel-optimization to squeeze out every single desibel that is possible to get. Voice coil cooling is very efficient and long excursion gives you a LOT of bass. 
Very linear impedance curve makes it possible to really extract all the power from the amp to these subwoofers.