RCF S8018-MK2 Passive 18" High-Efficiency Bass Reflex SubwooferThe RCF S8018 MK2 is engineered for live sound engineers and system integrators who require professional grade low frequency reinforcement without onboard amplification. The hypervented RCF Precision woofer and 4 inch inside outside voice coil minimize power compression under sustained touring loads, while the bass reflex cabinet design achieves efficient acoustic output starting at 30 Hzideal for music venues, theaters, clubs, and distributed