26mm dual ring radiator diaphragm with central phase correction plug. The low distortion response extends to above 40kHz which is exceptional for a tweeter in this price range. The tuned rear chamber yields a very low resonant frequency of 436 Hz which simplifies crossover design. The specially profiled 104mm diameter faceplate features recessed mounting holes for minimal reflection.
A full datasheet can be downloaded from the bottom of this page.