Capable of enduring 1,000 watts RMS all day and all night, the Celestion FTR18-4080HDX cast frame 18" pro woofer features a 4" high temperature Inside/Outside voice coil that efficiently dissipates heat and prevents the SPL losses caused by thermal compression. Extensive venting through the frame and motor structure also maximizes heat management. The FTR18-4080HDX multi-roll surround and double spider maintain excursion linearity, even at explosive output levels. This medium-Q driver performs well in all types of subwoofer enclosures. Direct replacement for Mackie SWA1501