Terminal Type - Push & insert style terminals for easy installation. Configuration - Round Surround / Cone Coupling - The pressure-treated double stitched foam surround along with the dual poly cotton spider helps keep the piston motion of the subwoofer linear and distortion-free. Voice Coil / Former Assembly - Vented aluminum former holds a 2.5' voice coil while allowing the heat to be exchanged. (Less heat means less distortion) Spider - Specialized MB Quart dual poly cotton spider with double centering allows the woofer to handle more power with minimum distortions. Frame / Venting Heavy-duty aluminum die-cast basket allows back venting, which exchanges heat with cool air, resulting in more power handling and increased reliability. Motor - Vented high-energy motor assembly with heavy-duty magnets increases power handling and increases SPL. Cone - Non-Pressed Paper Cone with Coating