Extended High Frequency Aluminum Ribbon Tweeter The Aluminum Ribbon Super Tweeter extends another 20,000+ Hertz above that, reaching up to 40,000 Hertz and providing an ultra smooth, clean high-frequency response for the ultimate listening experience. 6-Position Crossover Knob,The crossover knob allows you to activate the Super Tweeter at 8K, 10K, 12K, 14K, 16K or shut it off. 6-Position Treble Adjust Knob for Attenuation, If you love your Super Tweeter, but want a little less output, you can reduce the output by -1dB, -2dB, -3dB, -4dB or -5dB by re-positioning the Knob. It s an additional tweeter unit which covers a wide and extended high-frequency response, beyond that of your existing loudspeaker s integrated tweeters.