Original Factory Diaphragm 1450PB @ 8 Ohm. for 1450PB & 1450ZT 8 Ohm Driver . Fits Most Radian 1" Drivers SPECS: Overall Frame Diaphragm Diameter: 4.2" (107.2mm) Voice Coil Diameter: 1.74" (44.4mm) Diaphragm Material: Aluminium Alloy Dome with Vented Mylar Surround Nominal Impedance: 8 ohms Most Orders Placed Before 3PM and Paid thru PayPal Are Shipped The Same Day; Monday to Friday.