1 inch neodynium compression driver fits Alto Kick12,15 .and many others good replacement. Generic Driver Model Number G2500 Throat Diameter 1in(25mm) Mounting Type Screw on 1-3/8" Nominal Impedance 8 ohm Power Capacity 20Watts RMS Sensitivity(1W/1M) 106dB Frequency Range 1.5-18KHz Diaphragm Material phenolic Voice Coil Diameter 1 in(25.4mm) Voice Coil Material Round Copper Wire Flux Density 1.35T Magnet Material Neodymium N-38