JBL BassPro 8 Slot-Port Enclosure JBL's slot-port enclosure is engineered and "tuned" to the optimal frequency by the JBL engineering team. The enclosure material is MDF (medium-density fiberboard) to minimize resonances and unwanted ring. Lightweight but stiff polypropylene woofer cone provides clean reproduction and superior durability in an easy listening or high volume venue. Built-in Class D 100 watts RMS amplifier The JBL subwoofer system’s built-in amplifier provides electronics matched and optimized for woofer characteristics and enclosure acoustics. Class D operation also means the amplifier runs cooler and draws less current from the vehicle's electrical system. JBL RBC Wired Remote The RBC Wired Remote (optional) is an easy installation and can be mounted for convenient volume adjustment from the driver's seat, which sells separately on JBL website. Oversized Protection Bars The oversized protection bars project a "serious car audio enthusiast" statement, but more importantly they do an excellent job of protecting the speaker from accidental damage. Harman Standard Reliability Testing JBL speakers have to undergo a testing process that would destroy lesser speakers. JBL freezes them, bakes them, shakes them, blasts them with ultraviolet light and drives them at full power for days at a time. JBL at an Affordable Price This is JBL—the speaker and sound that has excited audio enthusiasts for over 70 years. And there's nothing better than riding with JBL sound.