Aluminum Super Tweeter - 4 Ohms Impedance.Die Cast Frame - Ferro Fluid Enhanced Voice Coil.1.75 inches High Temperature Kapton Voice Coil - Sensitivity: 102dB (1w/1m).Neodymium Magnet Structure - Frequency Response: 2k-20kHz.300 Watts RMS/600 Watts Rated Power - 4.52 inches Diameter/2.83 inches Mounting Depth The OPTIBT44 is a 600-watt, die-cast aluminum tweeter from Lanzar that really gets the highs rolling. With a frequency range of 2 to 20 kHz, you’ll have the top end covered. A 1.75 inches high-temperature Kapton voice coil and Neodymium magnet provide rich, sweet highs completely free of distortion. The die-cast frame ensures the security and longevity of your equipment. 4 ohm impedance.