Seismic Audio SA-DR9-8 Ohm Replacement Diaphragm - Compatible with Selenium D250-X Horn Drivers Model: SA-DR9 Contents: Replacement Diaphragm for Selenium D250-X horn driver Nominal Impedance: 8 Ohms Compatible with Selenium D250-X horn drivers Dimensions: Diameter: 4 Inches | Voice Coil Diameter: 2"