The Polk Audio db840DVC 8-inch dual voice coil subwoofer speaker is incredible sound at an affordable price. The polypropylene cone with rigid ABS dustcap stiffens the cone for greater mechanical stability and lower distortion. Marine Certified Polk db series speakers are built tough to withstand the toughest environments so they are perfect for use in boats of all types. That's why Correct Craft offers Polk Audio speakers in their award-winning Nautiques ski and wakeboarding boats. The db series subwoofers from Polk Audio are all about belting out deep, precise, stomach-shaking bass. The db Series Subs produce gutsy bass in sealed, ported and band pass enclosures. No matter how you like your bass, you get the tight, musical loud bass that db is known for.