SOUND TOWN ZS-118S210X4OC: The ZS-118S210X4OC line array set includes (1) ZETHUS-118S passive line array subwoofer, (4) ZETHUS-210B passive line array speakers, and (1) ZSCB-118S caster board ZETHUS-118S PASSIVE LINE ARRAY SUBWOOFER: The ZETHUS-118S passive line array subwoofer features an 18' woofer that operates at 800W RMS and has a program power output of 1600W (8-Ohm). Includes the ZSCB-118S caster board for hassle-free transportation (supports up to 660 lbs) ZETHUS-210B PASSIVE LINE ARRAY SPEAKER: The ZETHUS-210B line array speaker that comes with two 10' woofers and two 1.4' titanium compression drivers, delivering 550W RMS and 1100W program (16-Ohm) power handling capability, ensuring superior sound quality. Passive / bi-amp mode switchable for either quick connection or professional set up