26 mm Beryllium Tweeter8 ohm, Large Ring Neo, Black Faceplate, Grill- Beryllium Diaphragm (99% Pure Be)- Patented Symmetrical Drive (SD-2) motor- Black Anodized Machined Alu Faceplate- Rear Mount Magnet System- Titanium Voice Coil Former- Non Resonant Aluminium Rear Chamber LINK: Beryllium Safety Data Sheet