Sub-woofer series are the speaker of direct one(BW-515S, BW-8610S, and BW-S120) and under-pressure one (BW-S15 and BW-S18). The speaker cabinel is designed with innovative technology and newly established rocky paint finishing (21mm MDF with rocky pain finishing) which provide reliable reinforcement and long lasting outlook. High quality ultra-long range driver, high efficiency speaker system for sound reinforcement and monitoring, especially working with 7G, 8G and E series. The small size, high sensitivity and high power handing capacity of sub-woofer series make them an excellent choich for use in studios, clubs, bars, theatres and other applications (BW-8610S is an acctive sub-woofer, 500Watts)ModelBW-S15BW-S18Components:VLF 1x15" (380mm))VLF 1x18" (450mm)Connectors2xNEUTRIK NL42xNEUTRIK NL4Frequency Response:45Hz-280Hz± 3dB30Hz-250Hz± 3dBSensitivity(IW/IM)102dB100dBMaximum sound pressure115dB116dBRated Power600Watts700WattsMaximum Power1200Watts1400WattsNominal Impedance8 Ω8 ΩRecommended Amplifiers300 to 500Watts into 8Ω500 to700Watts into 8ΩHeight x Width x Depth535x525x705mm695x585x805mmWeight30kg45kg