Filter Filters $100-$500 18" Remove All Filters Condition New (3) Brand Harmony Audio (3) Voice Coils Dual (2) Sensitivity 88.4dB (2) Harmony Audio HA-ML181 Monolith 18" Competition Sub 3500W Dual 1 Ohm Subwoofer $379.95 (1) Harmony Audio HA-ML182 Monolith 18" Competition Sub 3500W Dual 2 Ohm Subwoofer $379.95 (2) Harmony Audio HA-BV1X18E Universal Single 18" Empty Vented Port Sub Box... $209.95