Scan speak R2004/602000

The compact size is one of the key elements of these Illuminator tweeters, which provides a high degree of flexibility within design options. The small size is employed without compromising sound quality where these compact tweeters are fully comparable to the renowned full size Illuminator and Revelator tweeters, no matter if the music is played at high or low listening levels.
Datasheet: Datasheet R2004/602000
Voice Coil, 01-2010

Size (inches): 0.75
Fs (Hz): 675
Re (ohms): 2.8
Sensitivity (dB): 86
Qt: 1.01
VAS (ltr.): 0.01
Xmax ± (mm): 0.4

Here you can soon find DIY kits for this driver.