Celestion's TF0818MR 8" professional midrange speaker features and integrated sealed chassis that isolates the driver's diaphragm a companion woofer's "back pressure", which eliminates the need to construct a separate sub-enclosure. The TF0818MR produces high-SPL, low distortion reproduction of the all-important frequency range. It features a 1.75" high-temp voice coil and a 31 oz. ceramic ferrite magnet, which contribute to the driver's very high output and low distortion.