- JBL's Thermalum woofer cone is a hybrid material that combines polypropylene and a nickel alloy. The combination of these two materials delivers a cone that is extremely rigid yet lightweight.<br>- Butyl Surrounds are used to guarantee long-term reliability by rejecting moisture and ultraviolet contamination.<br>- JBL's Neoglass tweeter provides flawless frequency response clear out to 22kHz.<br>- Stamped steel frame is used for easy fit into factory speaker locations.