The Classic tweeters are among the many highly praised designs in Classic series. They have enjoyed success over 3 decades. And still among the best tweeters available. The D2905/9000 tweeter kick-started a new era with a line of very high quality 1” tweeters, today known as -9300, -9500, -9700 and -9800. Despite their many years on the marked still used in many top High-End speakers around the world.
Datasheet: Datasheet D2905/970000

Size (inches): 1
Fs (Hz): 500
Re (ohms): 4.7
Sensitivity (dB): 89.5
Qt: 0.47
VAS (ltr.): 0.02
Xmax ± (mm): 0.4

Here you can soon find DIY kits for this driver.