DAS ACTION-S18 - Passive 18-Inch Subwoofer (Black)ACTION S18 is a passive direct radiation subwoofer system composed of a single 18FW speaker with a 3 coil and 20 mm winding depth, double layer and sandwich to boost system power, as well as a new forced convection circuit that works to reduce the effects of coil heating, improving the systems overall performance as a result. As part of a company culture, all DAS systems are developed under a single philosophy: to deliver the highest possible quality