Pioneer TS-W311D4 30 cm(12”) Champion series SubwooferPioneers TS W311D4 12 subwoofer is built to take it as well as dishing it out; featuring a ribbed cone thats injection molded for exceptional precision and strength. A double layered elastic polymer surround supports the woofer during cone excursion so youll get accurate, hard hitting bass notes even when the musics turned up loud. The dual 4 ohm voice coils allow you to wire the sub for 2 or 8 ohm impedance, so you get the flexibility you need to add