Alpine RS W10D4 10" Shallow Mount Subwoofer with Dual 4 Ohm Voice Coils (RSW10D4) DPUB820 Open architecture design provides plenty Mazda Open architecture design provides plenty of air circulation for convection cooling of components The Modular Design Construction future proofing technology from NAD was introduced in 2006 and enables owners of MDC capable components to add additional capabilities by inserting an extension module into an MDC slot on the rear panel Let's take a closer look at the key features that make the Alpine RS W10D4 an exceptional addition to your car audio system: You can enjoy extended listening sessions without concerns about overheating