More on Amazon.com : http://www.amazon.com/gp/product/B00BMBBLZO?tag=purrfectcatdi-20 Pair of SD-2 12D4 - Sundown Audio 12 Dual 4-Ohm Subwoofer SD212D4 Pair of SD-2 12D4 - Sundown Audio 12 Dual 4-Ohm Subwoofer SD212D4