The SL 218 is a professional passive subwoofer designed to enhance the ultra-low bass of an existing PA system. Like the active version SL 218 A, the SL 218 is also equipped with two 18" high performance loudspeakers, each of which operates in a separate chamber and can be driven by a separate amp. The total nominal power-handling capacity of the subwoofer is 2.000 W RMS (1.000 W per loudspeaker). The HK AUDIO® VX 2400 power amplifier would be an excellent match for the SL 218. If you are incorporating the SL 218 subwoofers into a DFC-controlled system, we would recommend that you use HK AUDIO® PR 8 or PR 16 power racks. The SL 218 comes equipped with four 100 mm wheels and is built to Eurotruck specs of 120 cm x 56 cm x 79 cm (47-1/2" x 22" x 31-1/8"). A wooden cover to protect the front grille during transport is included.