18-inch, cast aluminium chassis, ferrite magnet LF loudspeaker. PowerProX speakers are built for maximum performance and reliability throughout the lifespan of each speaker. Dynamic airflow venting delivers class-leading heat management with an average 20C lower voice coil temperature. Polysiloxane laminated dual suspension provides greater stability and improved cone displacement symmetry. Aluminium demodulation ring reduces harmonic and intermodulation distortion caused by voice coil displacement. Double-sided, weatherproof cone coating for moisture protection and enhanced durability.