Not quite satisfied with the incredible value of the Thunder4000 series subwoofers, MTX created a whole new monster! MTX Audio introduces a clever mix of leading-edge technology designed to play deep, low bass in a variety of enclosures: sealed, vented, free-air, or bandpass. The totally new Thunder4500 series features Spider Plateau Venting for cooler voice coil operation and greater reliability during heavy bass passages. Instead of pushing and pulling super-heated air over the voice coil like conventional, rear vented subwoofers, Thunder4500s shed the heat out the sides of the spider. The result is cooler operation during all-night crank-it-up bass sessions. Asymmetrical Linear Drive (ALD) technology, used on all MTX Audio Thunder subs, provides high output with low distortion, thanks to flat progressive spiders and extended pole pieces. These subs are packed with features to help dissipate heat and deliver thunderous bass output. Thunder4500 subs have rugged folded-window steel baskets, 1" voice coils