DESC: This design locks in air between the main cone and drive cone, ensuring smoother and more precise movement of the cones, for superior linearity. The locked-in air behaves like a spring, so there's no need for a traditional spider structure. The drive cone also deflects air pressure inside the enclosure, which further contributes to the remarkable bass of the small package.The Premier TS-SW1041D subwoofer is extremely flexible for installation, able to fit almost anywhere.